<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e043c-c83b-7501-856c-a2ea434ff3eb,g:e2dc1cbe-e942-4265-a5a3-164133e2ad52-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DocumentandEntityInformationDocument" xlink:type="simple" xlink:href="trs-20260630.xsd#DocumentandEntityInformationDocument"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DocumentandEntityInformationDocument" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_019e043c-c985-7963-a2f1-f4431eb3067b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntitiesTable_019e043c-c985-7963-a2f1-f4431eb3067b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019e043c-c985-72a9-bad6-f8ca311c280b" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntitiesTable_019e043c-c985-7963-a2f1-f4431eb3067b" xlink:to="loc_dei_LegalEntityAxis_019e043c-c985-72a9-bad6-f8ca311c280b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e043c-c985-72a9-bad6-f8ca311c280b_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019e043c-c985-72a9-bad6-f8ca311c280b" xlink:to="loc_dei_EntityDomain_019e043c-c985-72a9-bad6-f8ca311c280b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019e043c-c985-73e0-835d-390b3e6c9272" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019e043c-c985-72a9-bad6-f8ca311c280b" xlink:to="loc_dei_EntityDomain_019e043c-c985-73e0-835d-390b3e6c9272" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019e043c-c985-7b4d-aad6-f00118a6a26d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019e043c-c985-7b4d-aad6-f00118a6a26d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019e043c-c985-76ce-b6c9-2a1b12f2644d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_Security12bTitle_019e043c-c985-76ce-b6c9-2a1b12f2644d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_019e043c-c985-7578-8199-464afdec21b6" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_DocumentTransitionReport_019e043c-c985-7578-8199-464afdec21b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_019e043c-c985-77da-967f-1d471fde0272" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_DocumentQuarterlyReport_019e043c-c985-77da-967f-1d471fde0272" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019e043c-c985-7d0a-8f50-0a8e112009b8" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_DocumentPeriodEndDate_019e043c-c985-7d0a-8f50-0a8e112009b8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019e043c-c985-7bb4-b814-09d449ea474c" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_LocalPhoneNumber_019e043c-c985-7bb4-b814-09d449ea474c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019e043c-c985-703e-83f6-156c55474df3" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_CityAreaCode_019e043c-c985-703e-83f6-156c55474df3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019e043c-c985-7c9e-aa0c-e73b94b8114e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityAddressPostalZipCode_019e043c-c985-7c9e-aa0c-e73b94b8114e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019e043c-c985-718f-aee3-89ded62599c7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityAddressStateOrProvince_019e043c-c985-718f-aee3-89ded62599c7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019e043c-c985-7802-bb4e-9b828d9060cd" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityAddressCityOrTown_019e043c-c985-7802-bb4e-9b828d9060cd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine2_019e043c-c985-71d1-93b5-e03e4dcd9262" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityAddressAddressLine2_019e043c-c985-71d1-93b5-e03e4dcd9262" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019e043c-c985-75e4-955d-ff19563e589f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityAddressAddressLine1_019e043c-c985-75e4-955d-ff19563e589f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019e043c-c985-7b6a-9076-58ec18a27070" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityFileNumber_019e043c-c985-7b6a-9076-58ec18a27070" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_019e043c-c985-70ca-a580-57cffa5df3fb" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityShellCompany_019e043c-c985-70ca-a580-57cffa5df3fb" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_019e043c-c985-777b-a183-2a594e5476c7" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityInteractiveDataCurrent_019e043c-c985-777b-a183-2a594e5476c7" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_019e043c-c985-7569-9987-88e07d03a0f8" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityCurrentReportingStatus_019e043c-c985-7569-9987-88e07d03a0f8" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019e043c-c985-7187-a302-3c6247a42ac1" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityRegistrantName_019e043c-c985-7187-a302-3c6247a42ac1" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019e043c-c985-7815-9676-58716c79d53e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityCentralIndexKey_019e043c-c985-7815-9676-58716c79d53e" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_019e043c-c985-7a1e-8cc9-ead63e164336" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_CurrentFiscalYearEndDate_019e043c-c985-7a1e-8cc9-ead63e164336" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_019e043c-c985-753d-a72c-7a471b6bc99f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityFilerCategory_019e043c-c985-753d-a72c-7a471b6bc99f" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019e043c-c985-71b7-b3bb-09a26ace873e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_DocumentType_019e043c-c985-71b7-b3bb-09a26ace873e" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_019e043c-c985-70a7-8df6-9a7025d7b9d2" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_DocumentFiscalYearFocus_019e043c-c985-70a7-8df6-9a7025d7b9d2" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_019e043c-c985-7391-a494-950c9a7af44d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_DocumentFiscalPeriodFocus_019e043c-c985-7391-a494-950c9a7af44d" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019e043c-c985-77b9-936d-7928c065bc81" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_AmendmentFlag_019e043c-c985-77b9-936d-7928c065bc81" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_019e043c-c985-7f4e-81c6-e777b3940b1f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_019e043c-c985-7f4e-81c6-e777b3940b1f" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_019e043c-c985-7030-a54b-e8136cdc8e0f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntitySmallBusiness_019e043c-c985-7030-a54b-e8136cdc8e0f" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019e043c-c985-7b71-9d0a-b26ec8154045" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityEmergingGrowthCompany_019e043c-c985-7b71-9d0a-b26ec8154045" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019e043c-c985-7558-99be-1afda95595ff" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_TradingSymbol_019e043c-c985-7558-99be-1afda95595ff" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019e043c-c985-7407-8729-dbc39d7e98e9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_SecurityExchangeName_019e043c-c985-7407-8729-dbc39d7e98e9" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019e043c-c985-7c1f-8595-a7e577d47d21" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019e043c-c985-7aaa-ab3f-2c3bb60bb426" xlink:to="loc_dei_EntityTaxIdentificationNumber_019e043c-c985-7c1f-8595-a7e577d47d21" xlink:type="arc" order="29"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedBalanceSheetStatement" xlink:type="simple" xlink:href="trs-20260630.xsd#ConsolidatedBalanceSheetStatement"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedBalanceSheetStatement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e043c-c985-77d5-846f-647d4dd9e387" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e043c-c985-7abc-82ae-07b2a3332889" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-77d5-846f-647d4dd9e387" xlink:to="loc_us-gaap_StatementTable_019e043c-c985-7abc-82ae-07b2a3332889" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019e043c-c985-7f01-978d-da67ccd57d15" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e043c-c985-7abc-82ae-07b2a3332889" xlink:to="loc_srt_StatementScenarioAxis_019e043c-c985-7f01-978d-da67ccd57d15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7f01-978d-da67ccd57d15_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c985-7f01-978d-da67ccd57d15" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7f01-978d-da67ccd57d15_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-76bb-87de-f087e6c5a82b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c985-7f01-978d-da67ccd57d15" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-76bb-87de-f087e6c5a82b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-77d5-846f-647d4dd9e387" xlink:to="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e043c-c985-7332-b47c-194a4c65c1f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e043c-c985-7332-b47c-194a4c65c1f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019e043c-c985-7728-a5b8-ecca50901333" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019e043c-c985-7728-a5b8-ecca50901333" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_019e043c-c985-7b9c-904c-902f9da371ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:to="loc_us-gaap_InventoryNet_019e043c-c985-7b9c-904c-902f9da371ff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019e043c-c985-7770-a7c5-b1916b31353c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019e043c-c985-7770-a7c5-b1916b31353c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c985-7bdb-b420-c5d3cbfbfd02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c985-7bdb-b420-c5d3cbfbfd02" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019e043c-c985-7e97-b35a-eb6cdefbb62b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7fcb-acba-06966884469c" xlink:to="loc_us-gaap_AssetsCurrent_019e043c-c985-7e97-b35a-eb6cdefbb62b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019e043c-c985-7af8-afcc-fbff23731dba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019e043c-c985-7af8-afcc-fbff23731dba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e043c-c985-7544-8216-406d7aa6df93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e043c-c985-7544-8216-406d7aa6df93" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e043c-c985-7af3-83f6-d2b74e897f11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_Goodwill_019e043c-c985-7af3-83f6-d2b74e897f11" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e043c-c985-7ab8-9fe4-b1705e8b487e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019e043c-c985-7ab8-9fe4-b1705e8b487e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet_019e043c-c985-7dc4-bd14-647f4158f834" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_DeferredIncomeTaxAssetsNet_019e043c-c985-7dc4-bd14-647f4158f834" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019e043c-c985-793d-9fca-9cb005881529" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019e043c-c985-793d-9fca-9cb005881529" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_019e043c-c985-7380-a29f-6bb6d4a372f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_019e043c-c985-7380-a29f-6bb6d4a372f3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e043c-c985-7e31-98c4-159caa9da705" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019e043c-c985-749b-8932-f1843b01c9c8" xlink:to="loc_us-gaap_Assets_019e043c-c985-7e31-98c4-159caa9da705" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-77d5-846f-647d4dd9e387" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_019e043c-c985-7328-b90e-d7f3ad1fefaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:to="loc_us-gaap_DebtCurrent_019e043c-c985-7328-b90e-d7f3ad1fefaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019e043c-c985-7986-b8f6-24f25a3e339e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:to="loc_us-gaap_AccountsPayableCurrent_019e043c-c985-7986-b8f6-24f25a3e339e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_019e043c-c985-71b0-8a99-d3d6aabf04e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_019e043c-c985-71b0-8a99-d3d6aabf04e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LeaseLiabilitiesCurrentPortion_019e043c-c985-7d95-ac97-7c09891103c7" xlink:href="trs-20260630.xsd#trs_LeaseLiabilitiesCurrentPortion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:to="loc_trs_LeaseLiabilitiesCurrentPortion_019e043c-c985-7d95-ac97-7c09891103c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c985-717a-8110-a740b02f161f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c985-717a-8110-a740b02f161f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019e043c-c985-7414-9354-7e8b149bf9b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019e043c-c985-7fcc-b77e-18e909e75393" xlink:to="loc_us-gaap_LiabilitiesCurrent_019e043c-c985-7414-9354-7e8b149bf9b1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019e043c-c985-7282-887d-46031a9013ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019e043c-c985-7282-887d-46031a9013ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LeaseLiabilitiesNoncurrent_019e043c-c985-7c55-8d6e-3be9ebef1b95" xlink:href="trs-20260630.xsd#trs_LeaseLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_trs_LeaseLiabilitiesNoncurrent_019e043c-c985-7c55-8d6e-3be9ebef1b95" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019e043c-c985-7c38-82ef-f2dad0ae647e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019e043c-c985-7c38-82ef-f2dad0ae647e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_019e043c-c985-77f0-b614-a2349b384ab1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_019e043c-c985-77f0-b614-a2349b384ab1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_019e043c-c985-734e-874b-7f6621cf2f2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_019e043c-c985-734e-874b-7f6621cf2f2d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019e043c-c985-78c3-acb2-dcda2291e208" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_Liabilities_019e043c-c985-78c3-acb2-dcda2291e208" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_019e043c-c985-700c-bde3-0692326b0a15" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_PreferredStockValue_019e043c-c985-700c-bde3-0692326b0a15" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019e043c-c985-7e06-ac4a-bfae22be5dec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_CommonStockValue_019e043c-c985-7e06-ac4a-bfae22be5dec" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019e043c-c985-7bfd-a02c-4812ff350257" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019e043c-c985-7bfd-a02c-4812ff350257" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e043c-c985-7487-9fd2-6216dbd0bb02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e043c-c985-7487-9fd2-6216dbd0bb02" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-c985-7489-9368-1f3688d862fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-c985-7489-9368-1f3688d862fe" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e043c-c985-7f51-aaec-4dd7d25ff343" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_StockholdersEquity_019e043c-c985-7f51-aaec-4dd7d25ff343" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e043c-c985-7e5b-9d26-5db891c61dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019e043c-c985-77ba-9771-85ef564fe4a4" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e043c-c985-7e5b-9d26-5db891c61dcb" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedBalanceSheetParentheticals" xlink:type="simple" xlink:href="trs-20260630.xsd#ConsolidatedBalanceSheetParentheticals"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedBalanceSheetParentheticals" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e043c-c985-736e-a44e-5098de97b964" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_StatementTable_019e043c-c985-736e-a44e-5098de97b964" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019e043c-c985-7301-b333-4d342fdceb57" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e043c-c985-736e-a44e-5098de97b964" xlink:to="loc_srt_StatementScenarioAxis_019e043c-c985-7301-b333-4d342fdceb57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7301-b333-4d342fdceb57_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c985-7301-b333-4d342fdceb57" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7301-b333-4d342fdceb57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7a24-ae2d-880329ab5e5e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c985-7301-b333-4d342fdceb57" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7a24-ae2d-880329ab5e5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7541-9813-eb9c43082ed0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7541-9813-eb9c43082ed0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019e043c-c985-740a-8e2c-55c6b3a327fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019e043c-c985-7541-9813-eb9c43082ed0" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_019e043c-c985-740a-8e2c-55c6b3a327fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e043c-c985-7e18-bfc2-0db529608076" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAbstract_019e043c-c985-7e18-bfc2-0db529608076" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019e043c-c985-73f8-97ab-4f3048b23302" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019e043c-c985-73f8-97ab-4f3048b23302" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_019e043c-c985-74a3-a854-23b99cfcbffd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_019e043c-c985-74a3-a854-23b99cfcbffd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_019e043c-c985-7d55-abb5-c6b03844935f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_PreferredStockSharesIssued_019e043c-c985-7d55-abb5-c6b03844935f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_019e043c-c985-782c-afc2-7963b6d4978e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_019e043c-c985-782c-afc2-7963b6d4978e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019e043c-c985-7b5a-8835-355d798c8ca3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019e043c-c985-7b5a-8835-355d798c8ca3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_019e043c-c985-7c25-aea8-621f41b5c1cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_019e043c-c985-7c25-aea8-621f41b5c1cb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019e043c-c985-7b3f-bb0d-ba7177aabdc5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_CommonStockSharesIssued_019e043c-c985-7b3f-bb0d-ba7177aabdc5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019e043c-c985-7fe2-8534-acf4f72710d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-7123-a4ee-c26a149bbf6c" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019e043c-c985-7fe2-8534-acf4f72710d1" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementofIncome" xlink:type="simple" xlink:href="trs-20260630.xsd#ConsolidatedStatementofIncome"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementofIncome" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e043c-c985-748a-80d6-130774eb638f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_StatementTable_019e043c-c985-748a-80d6-130774eb638f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019e043c-c985-70cb-bc95-d68065a4dc41" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e043c-c985-748a-80d6-130774eb638f" xlink:to="loc_srt_StatementScenarioAxis_019e043c-c985-70cb-bc95-d68065a4dc41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-70cb-bc95-d68065a4dc41_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c985-70cb-bc95-d68065a4dc41" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-70cb-bc95-d68065a4dc41_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7100-88bc-c9915bd1c6fd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c985-70cb-bc95-d68065a4dc41" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c985-7100-88bc-c9915bd1c6fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e043c-c985-7ea8-81eb-b4ff9011e199" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_Revenues_019e043c-c985-7ea8-81eb-b4ff9011e199" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019e043c-c985-7679-86c9-d84127dcb74e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019e043c-c985-7679-86c9-d84127dcb74e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_019e043c-c985-7a31-a730-5a03ba4d6d45" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_GrossProfit_019e043c-c985-7a31-a730-5a03ba4d6d45" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e043c-c985-7762-8987-ff0ca0e7e5c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e043c-c985-7762-8987-ff0ca0e7e5c4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-c985-7f86-895c-17a61a6a37a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-c985-7f86-895c-17a61a6a37a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019e043c-c985-7f40-bd14-c3e297b3dabc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillAndIntangibleAssetImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019e043c-c985-7f40-bd14-c3e297b3dabc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019e043c-c985-736d-bdc5-5d2a78bca15c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_OperatingIncomeLoss_019e043c-c985-736d-bdc5-5d2a78bca15c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e043c-c985-7043-a1e6-b9c97b3a3cc8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e043c-c985-7043-a1e6-b9c97b3a3cc8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e043c-c985-7519-936b-ae3fc167e7d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e043c-c985-7043-a1e6-b9c97b3a3cc8" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e043c-c985-7519-936b-ae3fc167e7d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019e043c-c985-7aaa-b0f6-2f1b48fcc6cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e043c-c985-7043-a1e6-b9c97b3a3cc8" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019e043c-c985-7aaa-b0f6-2f1b48fcc6cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019e043c-c985-7507-9611-76215857f4af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e043c-c985-7043-a1e6-b9c97b3a3cc8" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019e043c-c985-7507-9611-76215857f4af" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019e043c-c985-7b2b-976d-e0599132e69e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_019e043c-c985-7043-a1e6-b9c97b3a3cc8" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019e043c-c985-7b2b-976d-e0599132e69e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e043c-c985-7814-bbaf-175904268f3d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e043c-c985-7814-bbaf-175904268f3d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e043c-c985-741d-8798-c166002fb4b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e043c-c985-741d-8798-c166002fb4b1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_019e043c-c985-702d-8361-d07ba9917f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_019e043c-c985-702d-8361-d07ba9917f9a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019e043c-c985-7773-88d9-767c833825f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019e043c-c985-7773-88d9-767c833825f2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e043c-c985-7fae-83bb-4b66c4df15d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_NetIncomeLoss_019e043c-c985-7fae-83bb-4b66c4df15d4" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_019e043c-c985-7c92-b6a3-95eea1987583" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_019e043c-c985-7c92-b6a3-95eea1987583" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_019e043c-c985-7c5d-b040-6d8e91ee0dfa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e043c-c985-7c92-b6a3-95eea1987583" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerBasicShare_019e043c-c985-7c5d-b040-6d8e91ee0dfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_019e043c-c985-78d4-8925-73411f840853" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e043c-c985-7c92-b6a3-95eea1987583" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_019e043c-c985-78d4-8925-73411f840853" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019e043c-c985-7fe0-b930-8999e2e31707" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e043c-c985-7c92-b6a3-95eea1987583" xlink:to="loc_us-gaap_EarningsPerShareBasic_019e043c-c985-7fe0-b930-8999e2e31707" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e043c-c985-7125-856f-02a20543797c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019e043c-c985-7c92-b6a3-95eea1987583" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e043c-c985-7125-856f-02a20543797c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedAbstract_019e043c-c985-73e6-92eb-655eb86d2d32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c985-79ee-8d58-0bbaf2728b25" xlink:to="loc_us-gaap_EarningsPerShareDilutedAbstract_019e043c-c985-73e6-92eb-655eb86d2d32" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_019e043c-c985-7b33-95bf-ad3ff78cc9e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e043c-c985-73e6-92eb-655eb86d2d32" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsPerDilutedShare_019e043c-c985-7b33-95bf-ad3ff78cc9e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_019e043c-c985-7386-b322-c08e9c9bc2b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e043c-c985-73e6-92eb-655eb86d2d32" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_019e043c-c985-7386-b322-c08e9c9bc2b6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019e043c-c985-7c4d-9459-4203b89b224a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e043c-c985-73e6-92eb-655eb86d2d32" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019e043c-c985-7c4d-9459-4203b89b224a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e043c-c985-7b74-a71c-b4b9b9471ef5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedAbstract_019e043c-c985-73e6-92eb-655eb86d2d32" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e043c-c985-7b74-a71c-b4b9b9471ef5" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementofCashFlowsStatement" xlink:type="simple" xlink:href="trs-20260630.xsd#ConsolidatedStatementofCashFlowsStatement"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementofCashFlowsStatement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e043c-c986-7f2e-a6e8-5b909d1abe6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:to="loc_us-gaap_StatementTable_019e043c-c986-7f2e-a6e8-5b909d1abe6b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019e043c-c986-7c39-941d-bac7cac2016a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e043c-c986-7f2e-a6e8-5b909d1abe6b" xlink:to="loc_srt_StatementScenarioAxis_019e043c-c986-7c39-941d-bac7cac2016a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c986-7c39-941d-bac7cac2016a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c986-7c39-941d-bac7cac2016a" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c986-7c39-941d-bac7cac2016a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019e043c-c986-780b-8f3c-90f5910e8386" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019e043c-c986-7c39-941d-bac7cac2016a" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019e043c-c986-780b-8f3c-90f5910e8386" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-780b-ba94-32067300557f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-780b-ba94-32067300557f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperations_019e043c-c986-7038-b3fa-08db369e792e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-780b-ba94-32067300557f" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperations_019e043c-c986-7038-b3fa-08db369e792e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019e043c-c986-75e3-a130-7aaf16862acd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-780b-ba94-32067300557f" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019e043c-c986-75e3-a130-7aaf16862acd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019e043c-c986-71d7-b3f8-2e08f8b9367a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-780b-ba94-32067300557f" xlink:to="loc_us-gaap_ProfitLoss_019e043c-c986-71d7-b3f8-2e08f8b9367a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-780b-ba94-32067300557f" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019e043c-c986-73a0-87d7-5070e58cd56b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillAndIntangibleAssetImpairment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_GoodwillAndIntangibleAssetImpairment_019e043c-c986-73a0-87d7-5070e58cd56b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_019e043c-c986-76d1-8a7c-31489d9924f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnDispositionOfAssets1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_019e043c-c986-76d1-8a7c-31489d9924f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019e043c-c986-7114-b0f7-4c4b723021f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_Depreciation_019e043c-c986-7114-b0f7-4c4b723021f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-c986-709e-b673-c168be12b9a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-c986-709e-b673-c168be12b9a8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019e043c-c986-739f-98af-f3f667ff7cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019e043c-c986-739f-98af-f3f667ff7cf6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019e043c-c986-7b7e-b83c-edf96c3907bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019e043c-c986-7b7e-b83c-edf96c3907bd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019e043c-c986-7d11-a7f9-08c97b6bec36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_ShareBasedCompensation_019e043c-c986-7d11-a7f9-08c97b6bec36" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_019e043c-c986-7db6-b8ee-6b79a64dedeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_019e043c-c986-7db6-b8ee-6b79a64dedeb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Increasedecreaseinasbestosliability_019e043c-c986-73a7-bfac-37e4fb96a610" xlink:href="trs-20260630.xsd#trs_Increasedecreaseinasbestosliability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_trs_Increasedecreaseinasbestosliability_019e043c-c986-73a7-bfac-37e4fb96a610" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalExpenseAndLiabilities_019e043c-c986-7440-b9e4-3e909e91a350" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnvironmentalExpenseAndLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_EnvironmentalExpenseAndLiabilities_019e043c-c986-7440-b9e4-3e909e91a350" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019e043c-c986-7b55-9345-f1cc9f725535" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019e043c-c986-7b55-9345-f1cc9f725535" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInReceivables_019e043c-c986-7818-891a-b4511f648180" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_IncreaseDecreaseInReceivables_019e043c-c986-7818-891a-b4511f648180" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_019e043c-c986-733c-9afd-d78a778e8f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_019e043c-c986-733c-9afd-d78a778e8f9a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019e043c-c986-76d4-887b-95b4f4fc6de4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019e043c-c986-76d4-887b-95b4f4fc6de4" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019e043c-c986-7a08-9338-f17c5b378e2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019e043c-c986-7a08-9338-f17c5b378e2a" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_019e043c-c986-7c5b-ad62-cb27f17277c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-7ebf-94c7-00eea90e0533" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_019e043c-c986-7c5b-ad62-cb27f17277c3" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e043c-c986-7b62-9a13-8230a8448462" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_019e043c-c986-780b-ba94-32067300557f" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e043c-c986-7b62-9a13-8230a8448462" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_019e043c-c986-797d-abd7-515828edc562" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_019e043c-c986-797d-abd7-515828edc562" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e043c-c986-77fc-aabe-b1cf0c33992e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e043c-c986-77fc-aabe-b1cf0c33992e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromHedgeInvestingActivities_019e043c-c986-780a-b7b3-d925d428a5f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForProceedsFromHedgeInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_PaymentsForProceedsFromHedgeInvestingActivities_019e043c-c986-780a-b7b3-d925d428a5f9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromDerivativeInstrumentInvestingActivities_019e043c-c986-7afd-bc3c-f9824c19b538" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForProceedsFromDerivativeInstrumentInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_PaymentsForProceedsFromDerivativeInstrumentInvestingActivities_019e043c-c986-7afd-bc3c-f9824c19b538" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-7b9d-afed-9c9dae5d3ae5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-7b9d-afed-9c9dae5d3ae5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_019e043c-c986-7e39-992b-c2ba33f3f77f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_019e043c-c986-7e39-992b-c2ba33f3f77f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_019e043c-c986-7f7e-b906-4c2a2414c910" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_019e043c-c986-7f7e-b906-4c2a2414c910" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e043c-c986-70a4-9dbe-38365d8817ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_019e043c-c986-76d3-aa8f-371d38b03283" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e043c-c986-70a4-9dbe-38365d8817ba" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019e043c-c986-78df-b9e9-d330b4fee11e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarlyRepaymentOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019e043c-c986-78df-b9e9-d330b4fee11e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_019e043c-c986-7ccc-b95d-4356cc274fb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_019e043c-c986-7ccc-b95d-4356cc274fb1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_019e043c-c986-7fc0-9f7a-547e78659c54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_019e043c-c986-7fc0-9f7a-547e78659c54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_019e043c-c986-736b-9992-523170f93022" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_019e043c-c986-736b-9992-523170f93022" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019e043c-c986-757a-8141-210ddf95022d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019e043c-c986-757a-8141-210ddf95022d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_019e043c-c986-7052-baac-d0dc0103dcb4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_019e043c-c986-7052-baac-d0dc0103dcb4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019e043c-c986-7f02-9db8-ec75799385ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019e043c-c986-7f02-9db8-ec75799385ee" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividends_019e043c-c986-7b14-98da-a1aeb7c64b88" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_PaymentsOfDividends_019e043c-c986-7b14-98da-a1aeb7c64b88" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019e043c-c986-7e1b-87da-5786f5846b70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_019e043c-c986-7e1b-87da-5786f5846b70" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_019e043c-c986-7d48-bfb5-c4d675a6b28e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations_019e043c-c986-7d48-bfb5-c4d675a6b28e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations_019e043c-c986-7c2e-a3c2-30d0ea764e6a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations_019e043c-c986-7c2e-a3c2-30d0ea764e6a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e043c-c986-76a7-a8c8-bc16040325ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_019e043c-c986-7d5a-81da-c0054907bb0a" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e043c-c986-76a7-a8c8-bc16040325ec" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e043c-c986-716d-8d0d-629233a29a4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e043c-c986-716d-8d0d-629233a29a4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019e043c-c986-7323-9381-6ed44895e490" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019e043c-c986-7323-9381-6ed44895e490" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019e043c-c986-7fc7-a600-0d3eeb143702" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_019e043c-c986-7185-9281-14d7426666b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SupplementalCashFlowInformationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7aff-a7c2-ce57d37b11b8" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_019e043c-c986-7185-9281-14d7426666b5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet_019e043c-c986-70d8-aa59-0f06e17d493d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_019e043c-c986-7185-9281-14d7426666b5" xlink:to="loc_us-gaap_InterestPaidNet_019e043c-c986-70d8-aa59-0f06e17d493d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaid_019e043c-c986-72e7-a30e-c78e810fc317" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxesPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_019e043c-c986-7185-9281-14d7426666b5" xlink:to="loc_us-gaap_IncomeTaxesPaid_019e043c-c986-72e7-a30e-c78e810fc317" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1_019e043c-c986-7aa1-a643-257a6c0abfa9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_019e043c-c986-7185-9281-14d7426666b5" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1_019e043c-c986-7aa1-a643-257a6c0abfa9" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/ConsolidatedStatementofShareholdersEquityStatement" xlink:type="simple" xlink:href="trs-20260630.xsd#ConsolidatedStatementofShareholdersEquityStatement"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/ConsolidatedStatementofShareholdersEquityStatement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019e043c-c986-757d-bb84-32d285ebc507" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_StatementTable_019e043c-c986-757d-bb84-32d285ebc507" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7841-9e86-78c581eb953b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019e043c-c986-757d-bb84-32d285ebc507" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7841-9e86-78c581eb953b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e043c-c986-7841-9e86-78c581eb953b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7841-9e86-78c581eb953b" xlink:to="loc_us-gaap_EquityComponentDomain_019e043c-c986-7841-9e86-78c581eb953b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e043c-c986-720d-bd71-b11d3325b4bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7841-9e86-78c581eb953b" xlink:to="loc_us-gaap_EquityComponentDomain_019e043c-c986-720d-bd71-b11d3325b4bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_019e043c-c986-7895-8c46-ea506833006c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e043c-c986-720d-bd71-b11d3325b4bd" xlink:to="loc_us-gaap_ParentMember_019e043c-c986-7895-8c46-ea506833006c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e043c-c986-7ffd-8d9a-603edb1d58bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019e043c-c986-7895-8c46-ea506833006c" xlink:to="loc_us-gaap_CommonStockMember_019e043c-c986-7ffd-8d9a-603edb1d58bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019e043c-c986-78a0-9dc6-f20db440a306" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019e043c-c986-7895-8c46-ea506833006c" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019e043c-c986-78a0-9dc6-f20db440a306" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019e043c-c986-77a0-9099-18adefbb90e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019e043c-c986-7895-8c46-ea506833006c" xlink:to="loc_us-gaap_RetainedEarningsMember_019e043c-c986-77a0-9099-18adefbb90e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e043c-c986-726e-b03f-2d36e7c916e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019e043c-c986-7895-8c46-ea506833006c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e043c-c986-726e-b03f-2d36e7c916e6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e043c-c986-7dcf-938c-f3f866cddb21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e043c-c986-7dcf-938c-f3f866cddb21" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e043c-c986-70da-b564-c4ec3d8a0e8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_NetIncomeLoss_019e043c-c986-70da-b564-c4ec3d8a0e8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e043c-c986-70d0-846f-c8670e9ccc69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e043c-c986-70d0-846f-c8670e9ccc69" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019e043c-c986-79e0-b684-8e2d196794da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019e043c-c986-79e0-b684-8e2d196794da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019e043c-c986-7b48-9ad6-43f63a1159f6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019e043c-c986-7b48-9ad6-43f63a1159f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019e043c-c986-7163-b2bc-935107251181" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019e043c-c986-7163-b2bc-935107251181" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_019e043c-c986-7573-aaa9-7cbcfda10c86" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_019e043c-c986-7573-aaa9-7cbcfda10c86" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e043c-c986-7aef-8d6b-321892e89765" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019e043c-c986-7aef-8d6b-321892e89765" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings_019e043c-c986-76d3-8f0f-3353da9e211c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings_019e043c-c986-76d3-8f0f-3353da9e211c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_019e043c-c986-7abd-8513-9a3f633f0cdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-c986-7a49-ba23-c1e9771fe374" xlink:to="loc_us-gaap_DividendsCommonStockCash_019e043c-c986-7abd-8513-9a3f633f0cdd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e043c-c986-7453-a097-fd119936663f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/BasisofPresentationSaleofAerospaceDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#BasisofPresentationSaleofAerospaceDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/BasisofPresentationSaleofAerospaceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-70b6-a297-5ba613f63729" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7b8d-812d-f91fc1b1bfc4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-70b6-a297-5ba613f63729" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7b8d-812d-f91fc1b1bfc4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-75d3-9405-473db4c15c4b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7b8d-812d-f91fc1b1bfc4" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-75d3-9405-473db4c15c4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-75d3-9405-473db4c15c4b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-75d3-9405-473db4c15c4b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-75d3-9405-473db4c15c4b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7aca-8921-5ff8ad30207a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-75d3-9405-473db4c15c4b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7aca-8921-5ff8ad30207a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LamonsDivisionMember_019e043c-c986-7ddd-a922-ad4d8946b2f4" xlink:href="trs-20260630.xsd#trs_LamonsDivisionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7aca-8921-5ff8ad30207a" xlink:to="loc_trs_LamonsDivisionMember_019e043c-c986-7ddd-a922-ad4d8946b2f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-777e-974a-e15f5c5870fc" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7aca-8921-5ff8ad30207a" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-777e-974a-e15f5c5870fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-70d0-8749-f6bdda5b6765" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7b8d-812d-f91fc1b1bfc4" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-70d0-8749-f6bdda5b6765" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-70d0-8749-f6bdda5b6765_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-70d0-8749-f6bdda5b6765" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-70d0-8749-f6bdda5b6765_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-71dd-9814-23b06a694a94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-70d0-8749-f6bdda5b6765" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-71dd-9814-23b06a694a94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019e043c-c986-7ffe-9289-39b13665e807" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-71dd-9814-23b06a694a94" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019e043c-c986-7ffe-9289-39b13665e807" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Purchasepricebasedondefinitivesalesagreement_019e043c-c986-734d-9a14-92288adf527a" xlink:href="trs-20260630.xsd#trs_Purchasepricebasedondefinitivesalesagreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-70b6-a297-5ba613f63729" xlink:to="loc_trs_Purchasepricebasedondefinitivesalesagreement_019e043c-c986-734d-9a14-92288adf527a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-755a-9d55-f0fbc94b49be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-70b6-a297-5ba613f63729" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-755a-9d55-f0fbc94b49be" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DiscontinuedOperationsSaleofAerospaceNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DiscontinuedOperationsSaleofAerospaceNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DiscontinuedOperationsSaleofAerospaceNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-75f0-8141-ab2a3c94a5e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-75f0-8141-ab2a3c94a5e0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7aca-9c13-e49e2d775b10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-75f0-8141-ab2a3c94a5e0" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7aca-9c13-e49e2d775b10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e043c-c986-7aca-9c13-e49e2d775b10_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7aca-9c13-e49e2d775b10" xlink:to="loc_us-gaap_EquityComponentDomain_019e043c-c986-7aca-9c13-e49e2d775b10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e043c-c986-7aa7-a056-d97b9fd29cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e043c-c986-7aca-9c13-e49e2d775b10" xlink:to="loc_us-gaap_EquityComponentDomain_019e043c-c986-7aa7-a056-d97b9fd29cb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e043c-c986-711e-8308-774925d56402" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e043c-c986-7aa7-a056-d97b9fd29cb5" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e043c-c986-711e-8308-774925d56402" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7afa-afb1-6db05f742f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-75f0-8141-ab2a3c94a5e0" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7afa-afb1-6db05f742f2b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7afa-afb1-6db05f742f2b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7afa-afb1-6db05f742f2b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7afa-afb1-6db05f742f2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-72b2-8436-78f52348caa3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7afa-afb1-6db05f742f2b" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-72b2-8436-78f52348caa3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LamonsDivisionMember_019e043c-c986-7a68-bda1-64a37f988b33" xlink:href="trs-20260630.xsd#trs_LamonsDivisionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-72b2-8436-78f52348caa3" xlink:to="loc_trs_LamonsDivisionMember_019e043c-c986-7a68-bda1-64a37f988b33" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-736e-8e0c-59c61e954d01" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-72b2-8436-78f52348caa3" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-736e-8e0c-59c61e954d01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-723d-9439-cbfe3393653e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-75f0-8141-ab2a3c94a5e0" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-723d-9439-cbfe3393653e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-723d-9439-cbfe3393653e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-723d-9439-cbfe3393653e" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-723d-9439-cbfe3393653e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7096-92d6-97c93bca8e3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-723d-9439-cbfe3393653e" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7096-92d6-97c93bca8e3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019e043c-c986-7562-8234-a3e083bf4910" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7096-92d6-97c93bca8e3a" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019e043c-c986-7562-8234-a3e083bf4910" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-c986-75db-95b8-e9e35e69a2eb" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-75f0-8141-ab2a3c94a5e0" xlink:to="loc_srt_RangeAxis_019e043c-c986-75db-95b8-e9e35e69a2eb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-c986-75db-95b8-e9e35e69a2eb_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-c986-75db-95b8-e9e35e69a2eb" xlink:to="loc_srt_RangeMember_019e043c-c986-75db-95b8-e9e35e69a2eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-c986-7390-ad5d-f85d5e553f30" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-c986-75db-95b8-e9e35e69a2eb" xlink:to="loc_srt_RangeMember_019e043c-c986-7390-ad5d-f85d5e553f30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-c986-70d6-9f70-05d5132d4bf0" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-c986-7390-ad5d-f85d5e553f30" xlink:to="loc_srt_MinimumMember_019e043c-c986-70d6-9f70-05d5132d4bf0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-c986-7b8b-98a0-cf80203862d8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-c986-7390-ad5d-f85d5e553f30" xlink:to="loc_srt_MaximumMember_019e043c-c986-7b8b-98a0-cf80203862d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-713d-af74-7764c5b3a0c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-75f0-8141-ab2a3c94a5e0" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-713d-af74-7764c5b3a0c4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-c986-713d-af74-7764c5b3a0c4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-713d-af74-7764c5b3a0c4" xlink:to="loc_us-gaap_SegmentDomain_019e043c-c986-713d-af74-7764c5b3a0c4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-c986-7def-9d87-6bf8caef13ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-713d-af74-7764c5b3a0c4" xlink:to="loc_us-gaap_SegmentDomain_019e043c-c986-7def-9d87-6bf8caef13ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateMember_019e043c-c986-7730-9c7a-f3b0b8218d77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-c986-7def-9d87-6bf8caef13ff" xlink:to="loc_us-gaap_CorporateMember_019e043c-c986-7730-9c7a-f3b0b8218d77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Purchasepricebasedondefinitivesalesagreement_019e043c-c986-7e5b-919c-e533740304cf" xlink:href="trs-20260630.xsd#trs_Purchasepricebasedondefinitivesalesagreement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_trs_Purchasepricebasedondefinitivesalesagreement_019e043c-c986-7e5b-919c-e533740304cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Proceedsonfinalizationofsaleofbusiness_019e043c-c986-7b89-9c0f-036d721ad1df" xlink:href="trs-20260630.xsd#trs_Proceedsonfinalizationofsaleofbusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_trs_Proceedsonfinalizationofsaleofbusiness_019e043c-c986-7b89-9c0f-036d721ad1df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-7da9-81a9-40fc0e7ea06c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-7da9-81a9-40fc0e7ea06c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-c986-763d-92cc-e5d79acdc91c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-c986-763d-92cc-e5d79acdc91c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentInterestRate_019e043c-c986-7c62-b8e2-6548c5d19354" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_us-gaap_InvestmentInterestRate_019e043c-c986-7c62-b8e2-6548c5d19354" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019e043c-c986-71de-b042-b9c53c5c52c5" xlink:href="trs-20260630.xsd#trs_MergersAcquisitionsDiligenceAndTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019e043c-c986-71de-b042-b9c53c5c52c5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019e043c-c986-72c3-bf33-57137752e6e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019e043c-c986-72c3-bf33-57137752e6e3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested_019e043c-c986-7a79-87d4-8420cebf7e6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_us-gaap_ProceedsFromDivestitureOfBusinessesNetOfCashDivested_019e043c-c986-7a79-87d4-8420cebf7e6e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019e043c-c986-7fa9-a525-02cfe895a245" xlink:href="trs-20260630.xsd#trs_DiscontinuedOperationNetGainOnDispositionsOfAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7e37-83ea-5490bce39b86" xlink:to="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019e043c-c986-7fa9-a525-02cfe895a245" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DiscontinuedOperationsResultsofDiscontinuedOperationsDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DiscontinuedOperationsResultsofDiscontinuedOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DiscontinuedOperationsResultsofDiscontinuedOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7779-8e8e-70a36dd337ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7779-8e8e-70a36dd337ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-760c-893c-fc4c7cb744ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7779-8e8e-70a36dd337ee" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-760c-893c-fc4c7cb744ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-760c-893c-fc4c7cb744ba_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-760c-893c-fc4c7cb744ba" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-760c-893c-fc4c7cb744ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-737f-b745-dfb9071ec15c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-760c-893c-fc4c7cb744ba" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-737f-b745-dfb9071ec15c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-745c-9f56-d52a5b0aaa12" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-737f-b745-dfb9071ec15c" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-745c-9f56-d52a5b0aaa12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-7b29-84d6-2d15d4d4bc1f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-7779-8e8e-70a36dd337ee" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-7b29-84d6-2d15d4d4bc1f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7b29-84d6-2d15d4d4bc1f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-7b29-84d6-2d15d4d4bc1f" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7b29-84d6-2d15d4d4bc1f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7756-9eae-761fe033a0d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019e043c-c986-7b29-84d6-2d15d4d4bc1f" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7756-9eae-761fe033a0d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019e043c-c986-7ff5-9ba3-12967edabb23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7756-9eae-761fe033a0d5" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_019e043c-c986-7ff5-9ba3-12967edabb23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_019e043c-c986-74b0-b75a-d6d9ca0c48d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019e043c-c986-7756-9eae-761fe033a0d5" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_019e043c-c986-74b0-b75a-d6d9ca0c48d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_019e043c-c986-73b5-89ce-3c634c710b5a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet_019e043c-c986-73b5-89ce-3c634c710b5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_019e043c-c986-7278-bc82-e33834818ec9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInventoryCurrent_019e043c-c986-7278-bc82-e33834818ec9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent_019e043c-c986-7d83-ae47-b806ea3432b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPrepaidAndOtherAssetsCurrent_019e043c-c986-7d83-ae47-b806ea3432b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c986-7626-8825-13f281e5dc66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c986-7626-8825-13f281e5dc66" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_019e043c-c986-7e8c-b7f6-f75ff2eef300" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentNoncurrent_019e043c-c986-7e8c-b7f6-f75ff2eef300" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAssets_019e043c-c986-7487-9833-0583b687dc07" xlink:href="trs-20260630.xsd#trs_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationOperatingLeaseRightOfUseAssets_019e043c-c986-7487-9833-0583b687dc07" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent_019e043c-c986-709f-b760-5a943ed37d28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGoodwillNoncurrent_019e043c-c986-709f-b760-5a943ed37d28" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent_019e043c-c986-7b91-a474-cf67ed72ea85" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsNoncurrent_019e043c-c986-7b91-a474-cf67ed72ea85" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_019e043c-c986-7a62-b4eb-d29dc2c69133" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentAssets_019e043c-c986-7a62-b4eb-d29dc2c69133" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_019e043c-c986-7f2c-85a1-8b14499d0c86" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation_019e043c-c986-7f2c-85a1-8b14499d0c86" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent_019e043c-c986-78d8-b4cb-9c31b7bfee8c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsPayableCurrent_019e043c-c986-78d8-b4cb-9c31b7bfee8c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent_019e043c-c986-71ac-ab96-d6f26847f354" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAccruedLiabilitiesCurrent_019e043c-c986-71ac-ab96-d6f26847f354" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilitiesCurrentPortion_019e043c-c986-7e87-9b54-6719dedf47cc" xlink:href="trs-20260630.xsd#trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilitiesCurrentPortion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilitiesCurrentPortion_019e043c-c986-7e87-9b54-6719dedf47cc" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c986-70a5-8016-a66b73433a8b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019e043c-c986-70a5-8016-a66b73433a8b" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilities_019e043c-c986-706c-a9b9-b0e679aa4e57" xlink:href="trs-20260630.xsd#trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationLeaseLiabilities_019e043c-c986-706c-a9b9-b0e679aa4e57" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_019e043c-c986-7284-85e7-8c715d0b77a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationDeferredTaxLiabilities_019e043c-c986-7284-85e7-8c715d0b77a3" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities_019e043c-c986-794e-8eec-3a90b9f007ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOtherNoncurrentLiabilities_019e043c-c986-794e-8eec-3a90b9f007ec" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_019e043c-c986-77be-bf14-359ec4b6d560" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation_019e043c-c986-77be-bf14-359ec4b6d560" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_019e043c-c986-7e8d-a062-9ed438390012" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_019e043c-c986-7e8d-a062-9ed438390012" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_019e043c-c986-78ca-8fca-ff4ddfb7620b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_019e043c-c986-78ca-8fca-ff4ddfb7620b" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss_019e043c-c986-7d26-a229-5ff757198d6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss_019e043c-c986-7d26-a229-5ff757198d6e" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationsSGA_019e043c-c986-71f4-bc0a-aa452206f646" xlink:href="trs-20260630.xsd#trs_DisposalGroupIncludingDiscontinuedOperationsSGA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationsSGA_019e043c-c986-71f4-bc0a-aa452206f646" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019e043c-c986-7013-a002-014f06d7a634" xlink:href="trs-20260630.xsd#trs_DiscontinuedOperationNetGainOnDispositionsOfAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_trs_DiscontinuedOperationNetGainOnDispositionsOfAssets_019e043c-c986-7013-a002-014f06d7a634" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss_019e043c-c986-74fd-8c44-5cdce2f10530" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss_019e043c-c986-74fd-8c44-5cdce2f10530" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense_019e043c-c986-7a09-8531-093a0a85eb72" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationInterestExpense_019e043c-c986-7a09-8531-093a0a85eb72" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationsOtherExpenseNet_019e043c-c986-739c-9b8d-fc04e1d4741b" xlink:href="trs-20260630.xsd#trs_DisposalGroupIncludingDiscontinuedOperationsOtherExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationsOtherExpenseNet_019e043c-c986-739c-9b8d-fc04e1d4741b" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DisposalGroupIncludingDiscontinuedOperationsNonoperatingExpense_019e043c-c986-753d-a5cc-3ea38b8f9e20" xlink:href="trs-20260630.xsd#trs_DisposalGroupIncludingDiscontinuedOperationsNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_trs_DisposalGroupIncludingDiscontinuedOperationsNonoperatingExpense_019e043c-c986-753d-a5cc-3ea38b8f9e20" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_019e043c-c986-70c9-a730-ab7cbdca8e1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_019e043c-c986-70c9-a730-ab7cbdca8e1d" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019e043c-c986-7c67-8c4c-418172d414b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_DiscontinuedOperationTaxEffectOfDiscontinuedOperation_019e043c-c986-7c67-8c4c-418172d414b3" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_019e043c-c986-78cb-81ad-c616d7c72ad5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_019e043c-c986-78cb-81ad-c616d7c72ad5" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019e043c-c986-7fdc-a1b5-eb89f6860771" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_Depreciation_019e043c-c986-7fdc-a1b5-eb89f6860771" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-c986-7965-bf10-df25a3d88ef6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-c986-7965-bf10-df25a3d88ef6" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019e043c-c986-711f-9cea-788ebe96d065" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_ShareBasedCompensation_019e043c-c986-711f-9cea-788ebe96d065" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_019e043c-c986-7a7d-abe4-8b456a8e0eba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnDispositionOfAssets1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_019e043c-c986-7a7d-abe4-8b456a8e0eba" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_019e043c-c986-7836-a1cc-956b117dda35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalExpenditureDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_CapitalExpenditureDiscontinuedOperations_019e043c-c986-7836-a1cc-956b117dda35" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e043c-c986-7b2b-8bfa-5dac990f10df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019e043c-c986-7bd3-b54c-f1818c617b85" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e043c-c986-7b2b-8bfa-5dac990f10df" xlink:type="arc" order="35"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#RevenueDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e043c-c986-7fe7-a05a-c7d9cb96227f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e043c-c986-7323-9bbd-bbadac83cfc0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e043c-c986-7fe7-a05a-c7d9cb96227f" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e043c-c986-7323-9bbd-bbadac83cfc0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019e043c-c986-7885-9062-9956c62885bd" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e043c-c986-7323-9bbd-bbadac83cfc0" xlink:to="loc_srt_MajorCustomersAxis_019e043c-c986-7885-9062-9956c62885bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e043c-c986-7885-9062-9956c62885bd_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019e043c-c986-7885-9062-9956c62885bd" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e043c-c986-7885-9062-9956c62885bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019e043c-c986-7eab-83f9-626fd9162c5b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019e043c-c986-7885-9062-9956c62885bd" xlink:to="loc_srt_NameOfMajorCustomerDomain_019e043c-c986-7eab-83f9-626fd9162c5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ConsumercustomerendmarketMember_019e043c-c986-782c-8583-cf2db9e68d9e" xlink:href="trs-20260630.xsd#trs_ConsumercustomerendmarketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019e043c-c986-7eab-83f9-626fd9162c5b" xlink:to="loc_trs_ConsumercustomerendmarketMember_019e043c-c986-782c-8583-cf2db9e68d9e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospacecustomerendmarketMember_019e043c-c986-71f4-ae22-a9ff1040bbb2" xlink:href="trs-20260630.xsd#trs_AerospacecustomerendmarketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019e043c-c986-7eab-83f9-626fd9162c5b" xlink:to="loc_trs_AerospacecustomerendmarketMember_019e043c-c986-71f4-ae22-a9ff1040bbb2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_IndustrialcustomerendmarketMember_019e043c-c986-78b2-9e9d-0dc7cd916a88" xlink:href="trs-20260630.xsd#trs_IndustrialcustomerendmarketMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019e043c-c986-7eab-83f9-626fd9162c5b" xlink:to="loc_trs_IndustrialcustomerendmarketMember_019e043c-c986-78b2-9e9d-0dc7cd916a88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e043c-c986-7480-8ed5-6caf3fce3026" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e043c-c986-7fe7-a05a-c7d9cb96227f" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e043c-c986-7480-8ed5-6caf3fce3026" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/RevenueContractAssetsLiabilitiesDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#RevenueContractAssetsLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RevenueContractAssetsLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostLineItems_019e41cb-f71a-7c5a-afd8-908b71f9d98d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostTable_019e41cb-f71a-7403-91a7-6191110d92a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CapitalizedContractCostTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e41cb-f71a-7c5a-afd8-908b71f9d98d" xlink:to="loc_us-gaap_CapitalizedContractCostTable_019e41cb-f71a-7403-91a7-6191110d92a9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetGross_019e41cb-f71a-7a71-9d88-93665f432a1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerAssetGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e41cb-f71a-7c5a-afd8-908b71f9d98d" xlink:to="loc_us-gaap_ContractWithCustomerAssetGross_019e41cb-f71a-7a71-9d88-93665f432a1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_019e41c1-7a5d-7e45-b150-819e9105695f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e41cb-f71a-7c5a-afd8-908b71f9d98d" xlink:to="loc_us-gaap_ContractWithCustomerLiability_019e41c1-7a5d-7e45-b150-819e9105695f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019e41ce-39ae-76f9-8387-a4ab7cb1bcd4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CapitalizedContractCostLineItems_019e41cb-f71a-7c5a-afd8-908b71f9d98d" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019e41ce-39ae-76f9-8387-a4ab7cb1bcd4" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/RealignmentActionsDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#RealignmentActionsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RealignmentActionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:href="trs-20260630.xsd#trs_RealignmentCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsTable_019e043c-c986-7cc0-a4e3-3e4dbbd1ae05" xlink:href="trs-20260630.xsd#trs_RealignmentActionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_RealignmentActionsTable_019e043c-c986-7cc0-a4e3-3e4dbbd1ae05" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-c986-77b2-b553-8f15c45b65c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_RealignmentActionsTable_019e043c-c986-7cc0-a4e3-3e4dbbd1ae05" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-c986-77b2-b553-8f15c45b65c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:href="trs-20260630.xsd#trs_RealignmentActionsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_RealignmentActionsTable_019e043c-c986-7cc0-a4e3-3e4dbbd1ae05" xlink:to="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsDomain_019e043c-c986-7b61-bdfd-659486a38e44_default" xlink:href="trs-20260630.xsd#trs_RealignmentActionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:to="loc_trs_RealignmentActionsDomain_019e043c-c986-7b61-bdfd-659486a38e44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsDomain_019e043c-c986-7b53-83b0-510216a9407f" xlink:href="trs-20260630.xsd#trs_RealignmentActionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:to="loc_trs_RealignmentActionsDomain_019e043c-c986-7b53-83b0-510216a9407f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsMember_019e043c-c986-783e-bb57-f204e72a28fc" xlink:href="trs-20260630.xsd#trs_RealignmentActionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentActionsDomain_019e043c-c986-7b53-83b0-510216a9407f" xlink:to="loc_trs_RealignmentActionsMember_019e043c-c986-783e-bb57-f204e72a28fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Realignmentcosts_019e043c-c986-7bcd-a5aa-a57e48b0b7e9" xlink:href="trs-20260630.xsd#trs_Realignmentcosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_Realignmentcosts_019e043c-c986-7bcd-a5aa-a57e48b0b7e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FacilityConsolidationRealignmentCosts_019e043c-c986-780d-b2fe-b62b7e9b9fd4" xlink:href="trs-20260630.xsd#trs_FacilityConsolidationRealignmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_FacilityConsolidationRealignmentCosts_019e043c-c986-780d-b2fe-b62b7e9b9fd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_EmployeeRelatedCosts_019e043c-c986-7dbf-a7f4-ac67a72bf8bd" xlink:href="trs-20260630.xsd#trs_EmployeeRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_EmployeeRelatedCosts_019e043c-c986-7dbf-a7f4-ac67a72bf8bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_019e043c-c986-7222-92a4-3d382367f54f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_SeveranceCosts1_019e043c-c986-7222-92a4-3d382367f54f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Cashpaidforseverance_019e043c-c986-7cf7-a31b-232072a96158" xlink:href="trs-20260630.xsd#trs_Cashpaidforseverance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_Cashpaidforseverance_019e043c-c986-7cf7-a31b-232072a96158" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019e043c-c986-7871-b5b3-a09e8aa982b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserveAcceleratedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019e043c-c986-7871-b5b3-a09e8aa982b7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWriteDown_019e043c-c986-7fe6-a943-93cb3259c027" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryWriteDown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_InventoryWriteDown_019e043c-c986-7fe6-a943-93cb3259c027" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019e043c-c986-7993-99bd-f29f7915dcdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_ShareBasedCompensation_019e043c-c986-7993-99bd-f29f7915dcdd" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/RealignmentActionsDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#RealignmentActionsDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/RealignmentActionsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:href="trs-20260630.xsd#trs_RealignmentCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsTable_019e043c-c986-7cc0-a4e3-3e4dbbd1ae05" xlink:href="trs-20260630.xsd#trs_RealignmentActionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_RealignmentActionsTable_019e043c-c986-7cc0-a4e3-3e4dbbd1ae05" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:href="trs-20260630.xsd#trs_RealignmentActionsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_RealignmentActionsTable_019e043c-c986-7cc0-a4e3-3e4dbbd1ae05" xlink:to="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsDomain_019e043c-c986-7b61-bdfd-659486a38e44_default" xlink:href="trs-20260630.xsd#trs_RealignmentActionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:to="loc_trs_RealignmentActionsDomain_019e043c-c986-7b61-bdfd-659486a38e44_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsDomain_019e043c-c986-7b53-83b0-510216a9407f" xlink:href="trs-20260630.xsd#trs_RealignmentActionsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_RealignmentActionsAxis_019e043c-c986-7b61-bdfd-659486a38e44" xlink:to="loc_trs_RealignmentActionsDomain_019e043c-c986-7b53-83b0-510216a9407f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentActionsMember_019e043c-c986-783e-bb57-f204e72a28fc" xlink:href="trs-20260630.xsd#trs_RealignmentActionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentActionsDomain_019e043c-c986-7b53-83b0-510216a9407f" xlink:to="loc_trs_RealignmentActionsMember_019e043c-c986-783e-bb57-f204e72a28fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Realignmentcosts_019e043c-c986-7bcd-a5aa-a57e48b0b7e9" xlink:href="trs-20260630.xsd#trs_Realignmentcosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_Realignmentcosts_019e043c-c986-7bcd-a5aa-a57e48b0b7e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FacilityConsolidationRealignmentCosts_019e043c-c986-780d-b2fe-b62b7e9b9fd4" xlink:href="trs-20260630.xsd#trs_FacilityConsolidationRealignmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_FacilityConsolidationRealignmentCosts_019e043c-c986-780d-b2fe-b62b7e9b9fd4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_EmployeeRelatedCosts_019e043c-c986-7dbf-a7f4-ac67a72bf8bd" xlink:href="trs-20260630.xsd#trs_EmployeeRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_EmployeeRelatedCosts_019e043c-c986-7dbf-a7f4-ac67a72bf8bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_019e043c-c986-7222-92a4-3d382367f54f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_SeveranceCosts1_019e043c-c986-7222-92a4-3d382367f54f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Cashpaidforseverance_019e043c-c986-7cf7-a31b-232072a96158" xlink:href="trs-20260630.xsd#trs_Cashpaidforseverance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_trs_Cashpaidforseverance_019e043c-c986-7cf7-a31b-232072a96158" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019e043c-c986-7871-b5b3-a09e8aa982b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringReserveAcceleratedDepreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_RestructuringReserveAcceleratedDepreciation_019e043c-c986-7871-b5b3-a09e8aa982b7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWriteDown_019e043c-c986-7fe6-a943-93cb3259c027" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryWriteDown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_InventoryWriteDown_019e043c-c986-7fe6-a943-93cb3259c027" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019e043c-c986-7993-99bd-f29f7915dcdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_RealignmentCostsLineItems_019e043c-c986-7367-b695-9ef79e8e6432" xlink:to="loc_us-gaap_ShareBasedCompensation_019e043c-c986-7993-99bd-f29f7915dcdd" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/AcquisitionsOtherAcquisitionsDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#AcquisitionsOtherAcquisitionsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/AcquisitionsOtherAcquisitionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e043c-c986-7d1f-85f5-8f4356255545" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e043c-c986-7d1f-85f5-8f4356255545" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e043c-c986-7573-b0b2-13c96ce0171a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019e043c-c986-7d1f-85f5-8f4356255545" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e043c-c986-7573-b0b2-13c96ce0171a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-c986-7573-b0b2-13c96ce0171a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e043c-c986-7573-b0b2-13c96ce0171a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-c986-7573-b0b2-13c96ce0171a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-c986-7188-9264-9c897899ba9b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e043c-c986-7573-b0b2-13c96ce0171a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-c986-7188-9264-9c897899ba9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_WeldmacManufacturingCompanyMember_019e043c-c986-736c-9a1b-fb823ceae44f" xlink:href="trs-20260630.xsd#trs_WeldmacManufacturingCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-c986-7188-9264-9c897899ba9b" xlink:to="loc_trs_WeldmacManufacturingCompanyMember_019e043c-c986-736c-9a1b-fb823ceae44f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_GMTAerospaceMember_019e043c-c986-7ca6-a64b-7cb7583da4b6" xlink:href="trs-20260630.xsd#trs_GMTAerospaceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-c986-7188-9264-9c897899ba9b" xlink:to="loc_trs_GMTAerospaceMember_019e043c-c986-7ca6-a64b-7cb7583da4b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e043c-c986-7467-98cd-0d2a26a8a55b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019e043c-c986-7467-98cd-0d2a26a8a55b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e043c-c986-791d-8268-d32df3873cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_Goodwill_019e043c-c986-791d-8268-d32df3873cb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019e043c-c986-7060-bfe0-cc884eb4ee8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019e043c-c986-7060-bfe0-cc884eb4ee8a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_BusinessCombinationRecognizedIdentifiableAssetsandLiabilitiesAssumedNetWorkingCapital_019e043c-c986-70ab-9694-1f2216658400" xlink:href="trs-20260630.xsd#trs_BusinessCombinationRecognizedIdentifiableAssetsandLiabilitiesAssumedNetWorkingCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_trs_BusinessCombinationRecognizedIdentifiableAssetsandLiabilitiesAssumedNetWorkingCapital_019e043c-c986-70ab-9694-1f2216658400" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019e043c-c986-7d09-b94f-1f27dd5b31bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019e043c-c986-7d09-b94f-1f27dd5b31bd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019e043c-c986-7a5e-8fe2-31bf1e9039a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019e043c-c986-7a5e-8fe2-31bf1e9039a7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_019e043c-c986-777f-92ac-a598df167e76" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_019e043c-c986-777f-92ac-a598df167e76" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow_019e043c-c986-7bae-95f0-053ed94c2491" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueLow_019e043c-c986-7bae-95f0-053ed94c2491" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_019e043c-c986-7fdb-af1e-286e90be4c47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_019e043c-c986-7fdb-af1e-286e90be4c47" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e043c-c986-749a-9cf4-3b75cd6bc257" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e043c-c986-749a-9cf4-3b75cd6bc257" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh_019e043c-c986-7bb8-80db-255b89cc9a80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInTheRangeOfOutcomesContingentConsiderationLiabilityValueHigh_019e043c-c986-7bb8-80db-255b89cc9a80" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019e043c-c986-7176-a37b-1f266dd81851" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-71fb-8595-658b6b282009" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019e043c-c986-7176-a37b-1f266dd81851" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/AcquisitionsSaleofBusinessDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#AcquisitionsSaleofBusinessDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/AcquisitionsSaleofBusinessDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-715d-9430-74a41e14a958" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-750d-9bc9-39fe490649a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-715d-9430-74a41e14a958" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-750d-9bc9-39fe490649a2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7e0a-978c-b955a018d36d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019e043c-c986-750d-9bc9-39fe490649a2" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7e0a-978c-b955a018d36d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7e0a-978c-b955a018d36d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7e0a-978c-b955a018d36d" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7e0a-978c-b955a018d36d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7c4f-9e06-949eca2fe3d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-c986-7e0a-978c-b955a018d36d" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7c4f-9e06-949eca2fe3d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ArrowEngineMember_019e043c-c986-7d85-8ea5-3d779db4a225" xlink:href="trs-20260630.xsd#trs_ArrowEngineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-c986-7c4f-9e06-949eca2fe3d5" xlink:to="loc_trs_ArrowEngineMember_019e043c-c986-7d85-8ea5-3d779db4a225" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-c986-76b3-bfa5-7edf729c1211" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-715d-9430-74a41e14a958" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-c986-76b3-bfa5-7edf729c1211" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-7157-a4b8-e9512153cc10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019e043c-c986-715d-9430-74a41e14a958" xlink:to="loc_us-gaap_ProceedsFromSalesOfBusinessAffiliateAndProductiveAssets_019e043c-c986-7157-a4b8-e9512153cc10" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-709b-99da-3cbaa8060e1e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-709b-99da-3cbaa8060e1e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_019e043c-c986-7481-ae48-9118f479e80e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputLongTermRevenueGrowthRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:to="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_019e043c-c986-7481-ae48-9118f479e80e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_019e043c-c986-70f3-8e6a-daf567f04c70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_019e043c-c986-70f3-8e6a-daf567f04c70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:href="trs-20260630.xsd#trs_QuantitativeImpairmentTestAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-74d4-b74d-1c5fef36ee89_default" xlink:href="trs-20260630.xsd#trs_QuantitativeImpairmentTestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:to="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-74d4-b74d-1c5fef36ee89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-76a6-9a35-62856ffd4c25" xlink:href="trs-20260630.xsd#trs_QuantitativeImpairmentTestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:to="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-76a6-9a35-62856ffd4c25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillMember_019e043c-c986-707c-a87b-c9e2448f51ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-76a6-9a35-62856ffd4c25" xlink:to="loc_us-gaap_GoodwillMember_019e043c-c986-707c-a87b-c9e2448f51ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-c986-74b9-9545-12b0b6ab2359_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:to="loc_us-gaap_SegmentDomain_019e043c-c986-74b9-9545-12b0b6ab2359_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-c986-75fa-8850-946613d133b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:to="loc_us-gaap_SegmentDomain_019e043c-c986-75fa-8850-946613d133b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-798a-8d5b-e902d60d057a" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-c986-75fa-8850-946613d133b3" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-798a-8d5b-e902d60d057a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-c986-7b6e-a933-1b3e31f9b1c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-c986-7b6e-a933-1b3e31f9b1c3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_019e043c-c986-7b93-be33-4c84febe42c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:to="loc_us-gaap_ReportingUnitDomain_019e043c-c986-7b93-be33-4c84febe42c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:to="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceFastenersReportingUnitMember_019e043c-c986-7d58-9b95-80b35c2d1fbf" xlink:href="trs-20260630.xsd#trs_AerospaceFastenersReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:to="loc_trs_AerospaceFastenersReportingUnitMember_019e043c-c986-7d58-9b95-80b35c2d1fbf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceEngineeredProductsReportingUnitMember_019e043c-c986-7f88-997e-40d7ec63517d" xlink:href="trs-20260630.xsd#trs_AerospaceEngineeredProductsReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:to="loc_trs_AerospaceEngineeredProductsReportingUnitMember_019e043c-c986-7f88-997e-40d7ec63517d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach_019e043c-ca3f-7cdf-b709-d87fea63cbda" xlink:href="trs-20260630.xsd#trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach_019e043c-ca3f-7cdf-b709-d87fea63cbda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach_019e043c-ca3f-779d-b222-ddec3e976a83" xlink:href="trs-20260630.xsd#trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach_019e043c-ca3f-779d-b222-ddec3e976a83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019e043c-ca3f-70c4-b72d-04cc623320d9" xlink:href="trs-20260630.xsd#trs_Fairvalueinputsvaluationmethoddiscountrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019e043c-ca3f-70c4-b72d-04cc623320d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethodresidualgrowthrate_019e043c-ca3f-7025-bcff-071420128825" xlink:href="trs-20260630.xsd#trs_Fairvalueinputsvaluationmethodresidualgrowthrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_Fairvalueinputsvaluationmethodresidualgrowthrate_019e043c-ca3f-7025-bcff-071420128825" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount_019e043c-ca3f-732a-b4dd-3fe5242ba9a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount_019e043c-ca3f-732a-b4dd-3fe5242ba9a2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019e043c-ca3f-7941-b6dc-81f14c10b10a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019e043c-ca3f-7941-b6dc-81f14c10b10a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInDiscountRate_019e043c-ca3f-74a9-a086-e24f6c1985cb" xlink:href="trs-20260630.xsd#trs_ChangeInDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInDiscountRate_019e043c-ca3f-74a9-a086-e24f6c1985cb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInTerminalGrowthRate_019e043c-ca3f-7177-b86a-0dd9c2317aba" xlink:href="trs-20260630.xsd#trs_ChangeInTerminalGrowthRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInTerminalGrowthRate_019e043c-ca3f-7177-b86a-0dd9c2317aba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate_019e043c-ca3f-7cd4-98b8-2409ba4f3c8b" xlink:href="trs-20260630.xsd#trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate_019e043c-ca3f-7cd4-98b8-2409ba4f3c8b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate_019e043c-ca3f-7714-8c8b-c94121ddd98d" xlink:href="trs-20260630.xsd#trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate_019e043c-ca3f-7714-8c8b-c94121ddd98d" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-709b-99da-3cbaa8060e1e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-709b-99da-3cbaa8060e1e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019e043c-c986-709b-99da-3cbaa8060e1e" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_019e043c-c986-7481-ae48-9118f479e80e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputLongTermRevenueGrowthRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:to="loc_us-gaap_MeasurementInputLongTermRevenueGrowthRateMember_019e043c-c986-7481-ae48-9118f479e80e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_019e043c-c986-70f3-8e6a-daf567f04c70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019e043c-c986-7790-abf7-b1b12c9ff889" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_019e043c-c986-70f3-8e6a-daf567f04c70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:href="trs-20260630.xsd#trs_QuantitativeImpairmentTestAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-74d4-b74d-1c5fef36ee89_default" xlink:href="trs-20260630.xsd#trs_QuantitativeImpairmentTestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:to="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-74d4-b74d-1c5fef36ee89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-76a6-9a35-62856ffd4c25" xlink:href="trs-20260630.xsd#trs_QuantitativeImpairmentTestDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_QuantitativeImpairmentTestAxis_019e043c-c986-74d4-b74d-1c5fef36ee89" xlink:to="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-76a6-9a35-62856ffd4c25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillMember_019e043c-c986-707c-a87b-c9e2448f51ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_QuantitativeImpairmentTestDomain_019e043c-c986-76a6-9a35-62856ffd4c25" xlink:to="loc_us-gaap_GoodwillMember_019e043c-c986-707c-a87b-c9e2448f51ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-c986-74b9-9545-12b0b6ab2359_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:to="loc_us-gaap_SegmentDomain_019e043c-c986-74b9-9545-12b0b6ab2359_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-c986-75fa-8850-946613d133b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-c986-74b9-9545-12b0b6ab2359" xlink:to="loc_us-gaap_SegmentDomain_019e043c-c986-75fa-8850-946613d133b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-798a-8d5b-e902d60d057a" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-c986-75fa-8850-946613d133b3" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-c986-798a-8d5b-e902d60d057a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-c986-71c4-aed4-f26af78eb708" xlink:to="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_019e043c-c986-7b93-be33-4c84febe42c0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:to="loc_us-gaap_ReportingUnitDomain_019e043c-c986-7b93-be33-4c84febe42c0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_019e043c-c986-7b93-be33-4c84febe42c0" xlink:to="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceFastenersReportingUnitMember_019e043c-c986-7d58-9b95-80b35c2d1fbf" xlink:href="trs-20260630.xsd#trs_AerospaceFastenersReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:to="loc_trs_AerospaceFastenersReportingUnitMember_019e043c-c986-7d58-9b95-80b35c2d1fbf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceEngineeredProductsReportingUnitMember_019e043c-c986-7f88-997e-40d7ec63517d" xlink:href="trs-20260630.xsd#trs_AerospaceEngineeredProductsReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_019e043c-c986-73cc-aaa1-1169cae567f1" xlink:to="loc_trs_AerospaceEngineeredProductsReportingUnitMember_019e043c-c986-7f88-997e-40d7ec63517d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach_019e043c-ca3f-7cdf-b709-d87fea63cbda" xlink:href="trs-20260630.xsd#trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedMarketBasedApproach_019e043c-ca3f-7cdf-b709-d87fea63cbda" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach_019e043c-ca3f-779d-b222-ddec3e976a83" xlink:href="trs-20260630.xsd#trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_FairValueInputsValuationMethodWeightingPercentageUsedIncomeBasedApproach_019e043c-ca3f-779d-b222-ddec3e976a83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019e043c-ca3f-70c4-b72d-04cc623320d9" xlink:href="trs-20260630.xsd#trs_Fairvalueinputsvaluationmethoddiscountrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019e043c-ca3f-70c4-b72d-04cc623320d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethodresidualgrowthrate_019e043c-ca3f-7025-bcff-071420128825" xlink:href="trs-20260630.xsd#trs_Fairvalueinputsvaluationmethodresidualgrowthrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_Fairvalueinputsvaluationmethodresidualgrowthrate_019e043c-ca3f-7025-bcff-071420128825" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount_019e043c-ca3f-732a-b4dd-3fe5242ba9a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount_019e043c-ca3f-732a-b4dd-3fe5242ba9a2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019e043c-ca3f-7941-b6dc-81f14c10b10a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019e043c-ca3f-7941-b6dc-81f14c10b10a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInDiscountRate_019e043c-ca3f-74a9-a086-e24f6c1985cb" xlink:href="trs-20260630.xsd#trs_ChangeInDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInDiscountRate_019e043c-ca3f-74a9-a086-e24f6c1985cb" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInTerminalGrowthRate_019e043c-ca3f-7177-b86a-0dd9c2317aba" xlink:href="trs-20260630.xsd#trs_ChangeInTerminalGrowthRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInTerminalGrowthRate_019e043c-ca3f-7177-b86a-0dd9c2317aba" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate_019e043c-ca3f-7cd4-98b8-2409ba4f3c8b" xlink:href="trs-20260630.xsd#trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInGoodwillImpairmentDueToChangeInDiscountRate_019e043c-ca3f-7cd4-98b8-2409ba4f3c8b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate_019e043c-ca3f-7714-8c8b-c94121ddd98d" xlink:href="trs-20260630.xsd#trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7c44-9639-c21e03d7bbea" xlink:to="loc_trs_ChangeInGoodwillImpairmentDueToChangeInTerminalRate_019e043c-ca3f-7714-8c8b-c94121ddd98d" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillRollforwardDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#GoodwillandOtherIntangibleAssetsGoodwillRollforwardDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsGoodwillRollforwardDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7691-a6f9-b83eedd5d017" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-ca3f-7b8c-a364-314353210826" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7691-a6f9-b83eedd5d017" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-ca3f-7b8c-a364-314353210826" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-7fb6-804b-f51cdc1d7f31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019e043c-ca3f-7b8c-a364-314353210826" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-7fb6-804b-f51cdc1d7f31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca3f-7fb6-804b-f51cdc1d7f31_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-7fb6-804b-f51cdc1d7f31" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca3f-7fb6-804b-f51cdc1d7f31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca3f-71a1-8311-9059c7571559" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-7fb6-804b-f51cdc1d7f31" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca3f-71a1-8311-9059c7571559" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PackagingReportableSegmentMember_019e043c-ca3f-7ad4-b2f0-a2bd254b4118" xlink:href="trs-20260630.xsd#trs_PackagingReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca3f-71a1-8311-9059c7571559" xlink:to="loc_trs_PackagingReportableSegmentMember_019e043c-ca3f-7ad4-b2f0-a2bd254b4118" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-ca3f-7841-9490-2c4f79e9ba01" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca3f-71a1-8311-9059c7571559" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-ca3f-7841-9490-2c4f79e9ba01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SpecialtyProductsReportableSegmentMember_019e043c-ca3f-7a04-a2ef-c3674cdadb6b" xlink:href="trs-20260630.xsd#trs_SpecialtyProductsReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca3f-71a1-8311-9059c7571559" xlink:to="loc_trs_SpecialtyProductsReportableSegmentMember_019e043c-ca3f-7a04-a2ef-c3674cdadb6b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7691-a6f9-b83eedd5d017" xlink:to="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e043c-ca3f-7ff9-94c3-2a9934f52689" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:to="loc_us-gaap_Goodwill_019e043c-ca3f-7ff9-94c3-2a9934f52689" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_019e043c-ca3f-71a5-b41b-857d9beef1c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_019e043c-ca3f-71a5-b41b-857d9beef1c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Goodwillreassignedbetweensegments_019e043c-ca3f-7578-9283-b3c085965b28" xlink:href="trs-20260630.xsd#trs_Goodwillreassignedbetweensegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:to="loc_trs_Goodwillreassignedbetweensegments_019e043c-ca3f-7578-9283-b3c085965b28" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019e043c-ca3f-7ae6-9db3-d44425b653c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019e043c-ca3f-7ae6-9db3-d44425b653c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_019e043c-ca3f-7ac9-baf9-b6f1e67b23bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:to="loc_us-gaap_GoodwillWrittenOffRelatedToSaleOfBusinessUnit_019e043c-ca3f-7ac9-baf9-b6f1e67b23bf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019e043c-ca3f-7d30-8b83-9014db9df3d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_019e043c-ca3f-714e-a9f4-20ce72bd1dd0" xlink:to="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019e043c-ca3f-7d30-8b83-9014db9df3d1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019e043c-ca3f-77ad-9113-f184ceabbd27" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019e043c-ca3f-71e9-a7d6-0752b0dee29e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019e043c-ca3f-7691-a6f9-b83eedd5d017" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019e043c-ca3f-71e9-a7d6-0752b0dee29e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsOtherIntangiblesNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#GoodwillandOtherIntangibleAssetsOtherIntangiblesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsOtherIntangiblesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019e043c-ca3f-7efa-9ee9-1b6fc46cfd6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019e043c-ca3f-74b3-8569-6f321f342de0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019e043c-ca3f-7efa-9ee9-1b6fc46cfd6b" xlink:to="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019e043c-ca3f-74b3-8569-6f321f342de0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7e76-871d-377aae0e5d2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019e043c-ca3f-74b3-8569-6f321f342de0" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7e76-871d-377aae0e5d2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7e76-871d-377aae0e5d2e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7e76-871d-377aae0e5d2e" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7e76-871d-377aae0e5d2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7a9c-a2cb-ca95905055dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7e76-871d-377aae0e5d2e" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7a9c-a2cb-ca95905055dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_019e043c-ca3f-778f-91c0-1a51784add9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7a9c-a2cb-ca95905055dd" xlink:to="loc_us-gaap_TradeNamesMember_019e043c-ca3f-778f-91c0-1a51784add9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-719d-8642-4776e3146f83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_019e043c-ca3f-74b3-8569-6f321f342de0" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-719d-8642-4776e3146f83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca3f-719d-8642-4776e3146f83_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-719d-8642-4776e3146f83" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca3f-719d-8642-4776e3146f83_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca3f-734c-bb8d-5f1eb29da940" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca3f-719d-8642-4776e3146f83" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca3f-734c-bb8d-5f1eb29da940" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-ca3f-75b7-bdd3-246f9c3cdc49" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca3f-734c-bb8d-5f1eb29da940" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-ca3f-75b7-bdd3-246f9c3cdc49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019e043c-ca3f-71e5-b99e-4b68aebdd942" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019e043c-ca3f-7efa-9ee9-1b6fc46cfd6b" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019e043c-ca3f-71e5-b99e-4b68aebdd942" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019e043c-ca3f-7759-ae94-dbde29e1771e" xlink:href="trs-20260630.xsd#trs_Fairvalueinputsvaluationmethoddiscountrate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_019e043c-ca3f-7efa-9ee9-1b6fc46cfd6b" xlink:to="loc_trs_Fairvalueinputsvaluationmethoddiscountrate_019e043c-ca3f-7759-ae94-dbde29e1771e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsexcludingGoodwillbyMajorClassDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsexcludingGoodwillbyMajorClassDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsexcludingGoodwillbyMajorClassDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019e043c-ca3f-7ef1-951f-8fcb5fbefeb9" xlink:href="trs-20260630.xsd#trs_IntangibleAssetsExcludingGoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019e043c-ca3f-79c0-a209-0a28975b967a" xlink:href="trs-20260630.xsd#trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019e043c-ca3f-7ef1-951f-8fcb5fbefeb9" xlink:to="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019e043c-ca3f-79c0-a209-0a28975b967a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca3f-7149-8fb7-6b2bc17890a5" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019e043c-ca3f-79c0-a209-0a28975b967a" xlink:to="loc_srt_RangeAxis_019e043c-ca3f-7149-8fb7-6b2bc17890a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca3f-7149-8fb7-6b2bc17890a5_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca3f-7149-8fb7-6b2bc17890a5" xlink:to="loc_srt_RangeMember_019e043c-ca3f-7149-8fb7-6b2bc17890a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca3f-768d-a30d-26894fe9cefc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca3f-7149-8fb7-6b2bc17890a5" xlink:to="loc_srt_RangeMember_019e043c-ca3f-768d-a30d-26894fe9cefc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca3f-7cdd-90f7-8a6ff3daed7a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca3f-768d-a30d-26894fe9cefc" xlink:to="loc_srt_MinimumMember_019e043c-ca3f-7cdd-90f7-8a6ff3daed7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca3f-7628-b8dc-110fdaef0e8b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca3f-768d-a30d-26894fe9cefc" xlink:to="loc_srt_MaximumMember_019e043c-ca3f-7628-b8dc-110fdaef0e8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019e043c-ca3f-7b06-9d23-d3cf9aa0e8e8" xlink:href="trs-20260630.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019e043c-ca3f-79c0-a209-0a28975b967a" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019e043c-ca3f-7b06-9d23-d3cf9aa0e8e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7b06-9d23-d3cf9aa0e8e8_default" xlink:href="trs-20260630.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019e043c-ca3f-7b06-9d23-d3cf9aa0e8e8" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7b06-9d23-d3cf9aa0e8e8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7263-aefb-f4e64a900e29" xlink:href="trs-20260630.xsd#trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeAxis_019e043c-ca3f-7b06-9d23-d3cf9aa0e8e8" xlink:to="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7263-aefb-f4e64a900e29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeFiveToTwelveYearsMember_019e043c-ca3f-77a3-b4e3-5f7ae37d6b34" xlink:href="trs-20260630.xsd#trs_UsefulLifeFiveToTwelveYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7263-aefb-f4e64a900e29" xlink:to="loc_trs_UsefulLifeFiveToTwelveYearsMember_019e043c-ca3f-77a3-b4e3-5f7ae37d6b34" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeFifteenToTwentyfiveYearsMember_019e043c-ca3f-7454-9465-cff586cfb2c8" xlink:href="trs-20260630.xsd#trs_UsefulLifeFifteenToTwentyfiveYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7263-aefb-f4e64a900e29" xlink:to="loc_trs_UsefulLifeFifteenToTwentyfiveYearsMember_019e043c-ca3f-7454-9465-cff586cfb2c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeOneToFifteenYearsMember_019e043c-ca3f-7758-aae2-3668f8313ddf" xlink:href="trs-20260630.xsd#trs_UsefulLifeOneToFifteenYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7263-aefb-f4e64a900e29" xlink:to="loc_trs_UsefulLifeOneToFifteenYearsMember_019e043c-ca3f-7758-aae2-3668f8313ddf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_UsefulLifeSeventeenToThirtyYearsMember_019e043c-ca3f-7231-b848-ab33f37577f0" xlink:href="trs-20260630.xsd#trs_UsefulLifeSeventeenToThirtyYearsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_FiniteLivedIntangibleAssetsByUsefulLifeDomain_019e043c-ca3f-7263-aefb-f4e64a900e29" xlink:to="loc_trs_UsefulLifeSeventeenToThirtyYearsMember_019e043c-ca3f-7231-b848-ab33f37577f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7209-a790-1fa01c3f54ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019e043c-ca3f-79c0-a209-0a28975b967a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7209-a790-1fa01c3f54ea" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7209-a790-1fa01c3f54ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7209-a790-1fa01c3f54ea" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7209-a790-1fa01c3f54ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-713c-b935-64e568c4db4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-7209-a790-1fa01c3f54ea" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-713c-b935-64e568c4db4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019e043c-ca3f-71d4-a5b1-adfe6f032b90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-713c-b935-64e568c4db4f" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019e043c-ca3f-71d4-a5b1-adfe6f032b90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019e043c-ca3f-775d-8ad8-8f6d8391e2ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-713c-b935-64e568c4db4f" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019e043c-ca3f-775d-8ad8-8f6d8391e2ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-72ef-aad5-f0a5cb25460e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfIntangibleAssetsExcludingGoodwillByMajorClassTable_019e043c-ca3f-79c0-a209-0a28975b967a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-72ef-aad5-f0a5cb25460e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-72ef-aad5-f0a5cb25460e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-72ef-aad5-f0a5cb25460e" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-72ef-aad5-f0a5cb25460e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7b2d-8634-e7067e04a0a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-72ef-aad5-f0a5cb25460e" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7b2d-8634-e7067e04a0a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_019e043c-ca3f-7205-8327-b2d89bd8b713" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7b2d-8634-e7067e04a0a0" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_019e043c-ca3f-7205-8327-b2d89bd8b713" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019e043c-ca3f-7293-9dfb-53a7db2bf8e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019e043c-ca3f-7ef1-951f-8fcb5fbefeb9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019e043c-ca3f-7293-9dfb-53a7db2bf8e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019e043c-ca3f-7b5a-98b3-0e3f019d9bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019e043c-ca3f-7ef1-951f-8fcb5fbefeb9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019e043c-ca3f-7b5a-98b3-0e3f019d9bf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e043c-ca3f-795b-af78-6c77e4e70fbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019e043c-ca3f-7ef1-951f-8fcb5fbefeb9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019e043c-ca3f-795b-af78-6c77e4e70fbb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019e043c-ca3f-7ca1-a0aa-695a3a12b7e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019e043c-ca3f-7ef1-951f-8fcb5fbefeb9" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019e043c-ca3f-7ca1-a0aa-695a3a12b7e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019e043c-ca3f-7c1d-ac89-2a762eb07b96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_IntangibleAssetsExcludingGoodwillLineItems_019e043c-ca3f-7ef1-951f-8fcb5fbefeb9" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019e043c-ca3f-7c1d-ac89-2a762eb07b96" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_AmortizationOfIntangibleAssetsLineItems_019e043c-ca3f-7a4c-908a-5a9db32ada11" xlink:href="trs-20260630.xsd#trs_AmortizationOfIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:href="trs-20260630.xsd#trs_ScheduleOfAmortizationOfIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_019e043c-ca3f-7a4c-908a-5a9db32ada11" xlink:to="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-76ff-ae44-7de9767314d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-76ff-ae44-7de9767314d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-70f8-a529-44aec41073be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-70f8-a529-44aec41073be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019e043c-ca3f-72dc-8989-8ad31f25eff1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019e043c-ca3f-72dc-8989-8ad31f25eff1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019e043c-ca3f-766a-a39a-5ef5192d3ea4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019e043c-ca3f-766a-a39a-5ef5192d3ea4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7a0a-9b62-e573539f364d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7a0a-9b62-e573539f364d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7678-8613-a608baee2f83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7678-8613-a608baee2f83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-71c6-b77b-c0ce6ccf767d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7678-8613-a608baee2f83" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-71c6-b77b-c0ce6ccf767d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-ca3f-7ca6-962a-bf14b973bae9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_019e043c-ca3f-7a4c-908a-5a9db32ada11" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-ca3f-7ca6-962a-bf14b973bae9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/GoodwillandOtherIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsAmortizationExpenseDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_AmortizationOfIntangibleAssetsLineItems_019e043c-ca3f-7a4c-908a-5a9db32ada11" xlink:href="trs-20260630.xsd#trs_AmortizationOfIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:href="trs-20260630.xsd#trs_ScheduleOfAmortizationOfIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_019e043c-ca3f-7a4c-908a-5a9db32ada11" xlink:to="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-70f8-a529-44aec41073be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-70f8-a529-44aec41073be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019e043c-ca3f-70f8-a529-44aec41073be" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019e043c-ca3f-72dc-8989-8ad31f25eff1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019e043c-ca3f-72dc-8989-8ad31f25eff1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019e043c-ca3f-766a-a39a-5ef5192d3ea4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019e043c-ca3f-7d19-bc86-ae700be7af1d" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019e043c-ca3f-766a-a39a-5ef5192d3ea4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfAmortizationOfIntangibleAssetsTable_019e043c-ca3f-745f-9a05-ed0855cb8e4b" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7a0a-9b62-e573539f364d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7a0a-9b62-e573539f364d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7678-8613-a608baee2f83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-7a0a-9b62-e573539f364d" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7678-8613-a608baee2f83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-71c6-b77b-c0ce6ccf767d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7678-8613-a608baee2f83" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-71c6-b77b-c0ce6ccf767d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-ca3f-7ca6-962a-bf14b973bae9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_AmortizationOfIntangibleAssetsLineItems_019e043c-ca3f-7a4c-908a-5a9db32ada11" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019e043c-ca3f-7ca6-962a-bf14b973bae9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyandEquipmentNetPropertyandEquipmentTableDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#PropertyandEquipmentNetPropertyandEquipmentTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyandEquipmentNetPropertyandEquipmentTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e043c-ca3f-7319-96a2-f57d26ca2805" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e043c-ca3f-7812-be62-43fd0da482ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e043c-ca3f-7319-96a2-f57d26ca2805" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e043c-ca3f-7812-be62-43fd0da482ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e043c-ca3f-72ca-9b8f-1f3e076d5e81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019e043c-ca3f-7812-be62-43fd0da482ee" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e043c-ca3f-72ca-9b8f-1f3e076d5e81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e043c-ca3f-72ca-9b8f-1f3e076d5e81_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e043c-ca3f-72ca-9b8f-1f3e076d5e81" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e043c-ca3f-72ca-9b8f-1f3e076d5e81_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e043c-ca3f-711f-a4ad-b1b7a6b27d8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019e043c-ca3f-72ca-9b8f-1f3e076d5e81" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e043c-ca3f-711f-a4ad-b1b7a6b27d8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndLandImprovementsMember_019e043c-ca3f-71be-8956-4616c32216bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LandAndLandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e043c-ca3f-711f-a4ad-b1b7a6b27d8e" xlink:to="loc_us-gaap_LandAndLandImprovementsMember_019e043c-ca3f-71be-8956-4616c32216bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_019e043c-ca3f-774d-8e59-117fa8078cbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e043c-ca3f-711f-a4ad-b1b7a6b27d8e" xlink:to="loc_us-gaap_BuildingMember_019e043c-ca3f-774d-8e59-117fa8078cbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_019e043c-ca3f-7223-8c67-6fae766f8567" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019e043c-ca3f-711f-a4ad-b1b7a6b27d8e" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_019e043c-ca3f-7223-8c67-6fae766f8567" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019e043c-ca3f-7253-b5a7-4aa56e932ab7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e043c-ca3f-7319-96a2-f57d26ca2805" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019e043c-ca3f-7253-b5a7-4aa56e932ab7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e043c-ca3f-72a3-b150-608754bcf21a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e043c-ca3f-7319-96a2-f57d26ca2805" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019e043c-ca3f-72a3-b150-608754bcf21a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019e043c-ca3f-756a-9ed3-e9f588055f47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019e043c-ca3f-7319-96a2-f57d26ca2805" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019e043c-ca3f-756a-9ed3-e9f588055f47" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyandEquipmentNetDepreciationExpenseTableDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#PropertyandEquipmentNetDepreciationExpenseTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyandEquipmentNetDepreciationExpenseTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_DepreciationExpenseLineItems_019e043c-ca3f-7406-ba69-912e7c577154" xlink:href="trs-20260630.xsd#trs_DepreciationExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfDepreciationExpenseTable_019e043c-ca3f-7299-a147-f3c009aef78b" xlink:href="trs-20260630.xsd#trs_ScheduleOfDepreciationExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_DepreciationExpenseLineItems_019e043c-ca3f-7406-ba69-912e7c577154" xlink:to="loc_trs_ScheduleOfDepreciationExpenseTable_019e043c-ca3f-7299-a147-f3c009aef78b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-791b-b1b1-e73093c2ca6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDepreciationExpenseTable_019e043c-ca3f-7299-a147-f3c009aef78b" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-791b-b1b1-e73093c2ca6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDepreciationExpenseTable_019e043c-ca3f-7299-a147-f3c009aef78b" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-77d0-9c02-d02a69761b3f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-77d0-9c02-d02a69761b3f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7259-8770-a6b298722a30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7259-8770-a6b298722a30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-7161-b22c-4c80dc1ec78a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7259-8770-a6b298722a30" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-7161-b22c-4c80dc1ec78a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019e043c-ca3f-75b7-9986-2b1d1ddb6826" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DepreciationExpenseLineItems_019e043c-ca3f-7406-ba69-912e7c577154" xlink:to="loc_us-gaap_Depreciation_019e043c-ca3f-75b7-9986-2b1d1ddb6826" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/PropertyandEquipmentNetDepreciationExpenseTableDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#PropertyandEquipmentNetDepreciationExpenseTableDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/PropertyandEquipmentNetDepreciationExpenseTableDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_trs_DepreciationExpenseLineItems_019e043c-ca3f-7406-ba69-912e7c577154" xlink:href="trs-20260630.xsd#trs_DepreciationExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfDepreciationExpenseTable_019e043c-ca3f-7299-a147-f3c009aef78b" xlink:href="trs-20260630.xsd#trs_ScheduleOfDepreciationExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_trs_DepreciationExpenseLineItems_019e043c-ca3f-7406-ba69-912e7c577154" xlink:to="loc_trs_ScheduleOfDepreciationExpenseTable_019e043c-ca3f-7299-a147-f3c009aef78b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDepreciationExpenseTable_019e043c-ca3f-7299-a147-f3c009aef78b" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-77d0-9c02-d02a69761b3f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-77d0-9c02-d02a69761b3f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7259-8770-a6b298722a30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca3f-77d0-9c02-d02a69761b3f" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7259-8770-a6b298722a30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-7161-b22c-4c80dc1ec78a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca3f-7259-8770-a6b298722a30" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca3f-7161-b22c-4c80dc1ec78a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019e043c-ca3f-75b7-9986-2b1d1ddb6826" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DepreciationExpenseLineItems_019e043c-ca3f-7406-ba69-912e7c577154" xlink:to="loc_us-gaap_Depreciation_019e043c-ca3f-75b7-9986-2b1d1ddb6826" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtDebtTableDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#LongtermDebtDebtTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtDebtTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-71a9-acf2-6937dc893cd3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-79b8-b349-5a3af3287354" xlink:href="trs-20260630.xsd#trs_ScheduleOfDebtInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-71a9-acf2-6937dc893cd3" xlink:to="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-79b8-b349-5a3af3287354" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-74ee-813d-d8c0e8c8c957" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-79b8-b349-5a3af3287354" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-74ee-813d-d8c0e8c8c957" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-74ee-813d-d8c0e8c8c957_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-74ee-813d-d8c0e8c8c957" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-74ee-813d-d8c0e8c8c957_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7efb-9448-78c4f1f7c7e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-74ee-813d-d8c0e8c8c957" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7efb-9448-78c4f1f7c7e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e043c-ca3f-724a-a3ca-267c76984671" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7efb-9448-78c4f1f7c7e9" xlink:to="loc_us-gaap_SeniorNotesMember_019e043c-ca3f-724a-a3ca-267c76984671" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CreditAgreementMember_019e043c-ca3f-769c-9217-5bab87d6605d" xlink:href="trs-20260630.xsd#trs_CreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7efb-9448-78c4f1f7c7e9" xlink:to="loc_trs_CreditAgreementMember_019e043c-ca3f-769c-9217-5bab87d6605d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019e043c-ca3f-74d3-8aac-037f127029a9" xlink:href="trs-20260630.xsd#trs_A4.875SeniorUnsecuredNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7efb-9448-78c4f1f7c7e9" xlink:to="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019e043c-ca3f-74d3-8aac-037f127029a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019e043c-ca3f-7ab5-be21-2dea06cb386d" xlink:href="trs-20260630.xsd#trs_A4125SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7efb-9448-78c4f1f7c7e9" xlink:to="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019e043c-ca3f-7ab5-be21-2dea06cb386d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_019e043c-ca3f-742d-be87-8ba74d72d8e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-71a9-acf2-6937dc893cd3" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_019e043c-ca3f-742d-be87-8ba74d72d8e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019e043c-ca3f-75a4-8b0a-b72cc7f9ab93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-71a9-acf2-6937dc893cd3" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019e043c-ca3f-75a4-8b0a-b72cc7f9ab93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019e043c-ca3f-71db-a69d-be5fc964e725" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-71a9-acf2-6937dc893cd3" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019e043c-ca3f-71db-a69d-be5fc964e725" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtSeniorNotesDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#LongtermDebtSeniorNotesDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtSeniorNotesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7dd7-b414-51279dacbfe8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7dd7-b414-51279dacbfe8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7aed-a3a6-c6b7ff0055b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7dd7-b414-51279dacbfe8" xlink:to="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7aed-a3a6-c6b7ff0055b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7aed-a3a6-c6b7ff0055b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7aed-a3a6-c6b7ff0055b8" xlink:to="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7aed-a3a6-c6b7ff0055b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7e64-bd84-3f95514e0cc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7aed-a3a6-c6b7ff0055b8" xlink:to="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7e64-bd84-3f95514e0cc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7d39-b21a-74cb56a8140e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7dd7-b414-51279dacbfe8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7d39-b21a-74cb56a8140e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7d39-b21a-74cb56a8140e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7d39-b21a-74cb56a8140e" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7d39-b21a-74cb56a8140e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7fb1-afdf-ca2a946a060f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7d39-b21a-74cb56a8140e" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7fb1-afdf-ca2a946a060f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca3f-73ef-b0bb-b5754b6075bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7fb1-afdf-ca2a946a060f" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca3f-73ef-b0bb-b5754b6075bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-74e9-b857-21d84cba9b9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7dd7-b414-51279dacbfe8" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-74e9-b857-21d84cba9b9f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-74e9-b857-21d84cba9b9f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-74e9-b857-21d84cba9b9f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-74e9-b857-21d84cba9b9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-765c-95ef-aa0c5b1fe08b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-74e9-b857-21d84cba9b9f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-765c-95ef-aa0c5b1fe08b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e043c-ca3f-7223-84f3-82750a4d0085" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-765c-95ef-aa0c5b1fe08b" xlink:to="loc_us-gaap_SeniorNotesMember_019e043c-ca3f-7223-84f3-82750a4d0085" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7226-bb33-86de3a5156f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7dd7-b414-51279dacbfe8" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7226-bb33-86de3a5156f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7226-bb33-86de3a5156f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7226-bb33-86de3a5156f4" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7226-bb33-86de3a5156f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7c1e-a838-72fc5b014d8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7226-bb33-86de3a5156f4" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7c1e-a838-72fc5b014d8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019e043c-ca3f-75f9-a762-889e3be984f0" xlink:href="trs-20260630.xsd#trs_A4.875SeniorUnsecuredNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7c1e-a838-72fc5b014d8f" xlink:to="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019e043c-ca3f-75f9-a762-889e3be984f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019e043c-ca3f-71cf-8888-b10bd495d9b0" xlink:href="trs-20260630.xsd#trs_A4125SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7c1e-a838-72fc5b014d8f" xlink:to="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019e043c-ca3f-71cf-8888-b10bd495d9b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019e043c-ca3f-7c2a-93b0-472d8452b8b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7dd7-b414-51279dacbfe8" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019e043c-ca3f-7c2a-93b0-472d8452b8b4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7c2a-93b0-472d8452b8b4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019e043c-ca3f-7c2a-93b0-472d8452b8b4" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7c2a-93b0-472d8452b8b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7742-a525-5d3c6d8eb16e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019e043c-ca3f-7c2a-93b0-472d8452b8b4" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7742-a525-5d3c6d8eb16e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019e043c-ca3f-7b19-9370-5957d5fb1437" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7742-a525-5d3c6d8eb16e" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019e043c-ca3f-7b19-9370-5957d5fb1437" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019e043c-ca3f-7525-b7f2-f0ba6b5da09e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7742-a525-5d3c6d8eb16e" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019e043c-ca3f-7525-b7f2-f0ba6b5da09e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_019e043c-ca3f-79bd-bc79-a666fa894c9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7742-a525-5d3c6d8eb16e" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_019e043c-ca3f-79bd-bc79-a666fa894c9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_019e043c-ca3f-75d5-969e-ac2f39d50054" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019e043c-ca3f-7742-a525-5d3c6d8eb16e" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_019e043c-ca3f-75d5-969e-ac2f39d50054" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019e043c-ca3f-75cc-9a55-059058b86aa8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019e043c-ca3f-75cc-9a55-059058b86aa8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e043c-ca3f-7100-9b22-1d34720aa72c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019e043c-ca3f-7100-9b22-1d34720aa72c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_019e043c-ca3f-7ff1-b11c-eb3dba3708b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_019e043c-ca3f-7ff1-b11c-eb3dba3708b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_019e043c-ca3f-70bf-b720-02d3c70cdad2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_RepaymentsOfDebt_019e043c-ca3f-70bf-b720-02d3c70cdad2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_019e043c-ca3f-7b18-9de0-e0392b523651" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_019e043c-ca3f-7b18-9de0-e0392b523651" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019e043c-ca3f-788d-94b0-c7587983961f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019e043c-ca3f-788d-94b0-c7587983961f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019e043c-ca3f-7767-a1b8-36226defe0f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019e043c-ca3f-7767-a1b8-36226defe0f8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentDateOfFirstRequiredPayment1_019e043c-ca3f-79dc-828a-ac841f279d63" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentDateOfFirstRequiredPayment1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentDateOfFirstRequiredPayment1_019e043c-ca3f-79dc-828a-ac841f279d63" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering_019e043c-ca3f-7cf0-ab1d-be47801dd8a7" xlink:href="trs-20260630.xsd#trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_trs_Percentageofprincipalthatcanberedeemedwithcashproceedsfromanequityoffering_019e043c-ca3f-7cf0-ab1d-be47801dd8a7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering_019e043c-ca3f-72a5-833c-a3b4a84be0b3" xlink:href="trs-20260630.xsd#trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_trs_Debtinstrumentredemptionpricewithnetproceedsfromequityoffering_019e043c-ca3f-72a5-833c-a3b4a84be0b3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019e043c-ca3f-7929-adbd-ba231b8d6a3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019e043c-ca3f-7929-adbd-ba231b8d6a3b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019e043c-ca3f-77ca-9f16-c415fd91409b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarlyRepaymentOfSeniorDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_EarlyRepaymentOfSeniorDebt_019e043c-ca3f-77ca-9f16-c415fd91409b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFeeAmount_019e043c-ca3f-7273-9567-0bd9e4ded7ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentFeeAmount_019e043c-ca3f-7273-9567-0bd9e4ded7ee" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFee_019e043c-ca3f-7c5b-a122-63ba966a9a49" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_us-gaap_DebtInstrumentFee_019e043c-ca3f-7c5b-a122-63ba966a9a49" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AccruedInterestPaidThroughRedemptionDate_019e043c-ca3f-7255-8ce1-18fe95b76ac1" xlink:href="trs-20260630.xsd#trs_AccruedInterestPaidThroughRedemptionDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7d8b-a774-60b95dd5facd" xlink:to="loc_trs_AccruedInterestPaidThroughRedemptionDate_019e043c-ca3f-7255-8ce1-18fe95b76ac1" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtCreditAgreementDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#LongtermDebtCreditAgreementDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtCreditAgreementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-765a-b426-5847d86121d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-765a-b426-5847d86121d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-765a-b426-5847d86121d8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-765a-b426-5847d86121d8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-765a-b426-5847d86121d8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-76ba-ad22-0c8a98bdec79" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-765a-b426-5847d86121d8" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-76ba-ad22-0c8a98bdec79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_BankdebtandreceivablesfacilityMember_019e043c-ca3f-743a-9dd2-c79687e9631c" xlink:href="trs-20260630.xsd#trs_BankdebtandreceivablesfacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-76ba-ad22-0c8a98bdec79" xlink:to="loc_trs_BankdebtandreceivablesfacilityMember_019e043c-ca3f-743a-9dd2-c79687e9631c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RevolvingCreditAndTermLoanFacilitiesMember_019e043c-ca3f-7760-a2c1-0ec03c5079d4" xlink:href="trs-20260630.xsd#trs_RevolvingCreditAndTermLoanFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-76ba-ad22-0c8a98bdec79" xlink:to="loc_trs_RevolvingCreditAndTermLoanFacilitiesMember_019e043c-ca3f-7760-a2c1-0ec03c5079d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-76a2-8310-96aa79e83611" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-76ba-ad22-0c8a98bdec79" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-76a2-8310-96aa79e83611" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-70a8-9611-111cf54ca287" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-70a8-9611-111cf54ca287" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-70a8-9611-111cf54ca287_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-70a8-9611-111cf54ca287" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-70a8-9611-111cf54ca287_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7583-9ff6-cb9c66120177" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-70a8-9611-111cf54ca287" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7583-9ff6-cb9c66120177" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca3f-76c3-8370-6aa524826745" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7583-9ff6-cb9c66120177" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca3f-76c3-8370-6aa524826745" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7f4a-826e-35ab5415b037" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:to="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7f4a-826e-35ab5415b037" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7f4a-826e-35ab5415b037_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7f4a-826e-35ab5415b037" xlink:to="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7f4a-826e-35ab5415b037_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7ecb-b327-2792b953bc9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7f4a-826e-35ab5415b037" xlink:to="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7ecb-b327-2792b953bc9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_TermloanAfacilityMember_019e043c-ca3f-7430-90f5-4eddd731d26e" xlink:href="trs-20260630.xsd#trs_TermloanAfacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7ecb-b327-2792b953bc9e" xlink:to="loc_trs_TermloanAfacilityMember_019e043c-ca3f-7430-90f5-4eddd731d26e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7b61-8dea-5c782bfde6c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7ecb-b327-2792b953bc9e" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7b61-8dea-5c782bfde6c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019e043c-ca3f-7113-aac7-d02bb26ded05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7ecb-b327-2792b953bc9e" xlink:to="loc_us-gaap_LetterOfCreditMember_019e043c-ca3f-7113-aac7-d02bb26ded05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-710f-a0b6-3f7a945c3200" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-710f-a0b6-3f7a945c3200" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-710f-a0b6-3f7a945c3200_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-710f-a0b6-3f7a945c3200" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-710f-a0b6-3f7a945c3200_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7976-b84e-5f2ab75d559e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-710f-a0b6-3f7a945c3200" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7976-b84e-5f2ab75d559e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7b5d-8057-e2f18122a2fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7976-b84e-5f2ab75d559e" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7b5d-8057-e2f18122a2fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SeniorSecuredTermLoanMember_019e043c-ca3f-75ed-88de-9eb2f24083d2" xlink:href="trs-20260630.xsd#trs_SeniorSecuredTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7976-b84e-5f2ab75d559e" xlink:to="loc_trs_SeniorSecuredTermLoanMember_019e043c-ca3f-75ed-88de-9eb2f24083d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionAxis_019e043c-ca3f-7e00-aa8f-3cd291f6186b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeographicDistributionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:to="loc_us-gaap_GeographicDistributionAxis_019e043c-ca3f-7e00-aa8f-3cd291f6186b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomain_019e043c-ca3f-7e00-aa8f-3cd291f6186b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeographicDistributionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GeographicDistributionAxis_019e043c-ca3f-7e00-aa8f-3cd291f6186b" xlink:to="loc_us-gaap_GeographicDistributionDomain_019e043c-ca3f-7e00-aa8f-3cd291f6186b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomain_019e043c-ca3f-7e56-89c8-2f5e0f3aaf07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeographicDistributionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GeographicDistributionAxis_019e043c-ca3f-7e00-aa8f-3cd291f6186b" xlink:to="loc_us-gaap_GeographicDistributionDomain_019e043c-ca3f-7e56-89c8-2f5e0f3aaf07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionForeignMember_019e043c-ca3f-7c66-abe5-35c374dcaea1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeographicDistributionForeignMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeographicDistributionDomain_019e043c-ca3f-7e56-89c8-2f5e0f3aaf07" xlink:to="loc_us-gaap_GeographicDistributionForeignMember_019e043c-ca3f-7c66-abe5-35c374dcaea1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomesticMember_019e043c-ca3f-7d22-888f-2c6e7beb6f7c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeographicDistributionDomesticMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeographicDistributionDomain_019e043c-ca3f-7e56-89c8-2f5e0f3aaf07" xlink:to="loc_us-gaap_GeographicDistributionDomesticMember_019e043c-ca3f-7d22-888f-2c6e7beb6f7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca3f-7e6c-82f8-d7ee015990ee" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7de0-963b-46251fc74e2b" xlink:to="loc_srt_RangeAxis_019e043c-ca3f-7e6c-82f8-d7ee015990ee" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca3f-7e6c-82f8-d7ee015990ee_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca3f-7e6c-82f8-d7ee015990ee" xlink:to="loc_srt_RangeMember_019e043c-ca3f-7e6c-82f8-d7ee015990ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca3f-79e2-882a-bc4fd676ab69" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca3f-7e6c-82f8-d7ee015990ee" xlink:to="loc_srt_RangeMember_019e043c-ca3f-79e2-882a-bc4fd676ab69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca3f-7260-990c-72329c39013d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca3f-79e2-882a-bc4fd676ab69" xlink:to="loc_srt_MinimumMember_019e043c-ca3f-7260-990c-72329c39013d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca3f-759b-a566-b901655c68aa" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca3f-79e2-882a-bc4fd676ab69" xlink:to="loc_srt_MaximumMember_019e043c-ca3f-759b-a566-b901655c68aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_019e043c-ca3f-71c6-a079-ff03d443054d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_019e043c-ca3f-71c6-a079-ff03d443054d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019e043c-ca3f-7a04-8979-b9158d7ef63e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_019e043c-ca3f-7a04-8979-b9158d7ef63e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019e043c-ca3f-7a8d-b762-6969036c03e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019e043c-ca3f-7a8d-b762-6969036c03e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_019e043c-ca3f-74b9-bc95-d127ef03cea2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WriteOffOfDeferredDebtIssuanceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_WriteOffOfDeferredDebtIssuanceCost_019e043c-ca3f-74b9-bc95-d127ef03cea2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_019e043c-ca3f-7560-91d6-d2ae1e9a2768" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_019e043c-ca3f-7560-91d6-d2ae1e9a2768" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e043c-ca3f-7b69-b071-ee49ea293408" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e043c-ca3f-7b69-b071-ee49ea293408" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_019e043c-ca3f-735e-b751-45f16379b365" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_019e043c-ca3f-735e-b751-45f16379b365" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019e043c-ca3f-7830-b73a-ffa352713018" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019e043c-ca3f-7830-b73a-ffa352713018" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e043c-ca3f-73c1-aa94-6398d2ec043b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e043c-ca3f-73c1-aa94-6398d2ec043b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_IncrementalDebtCommitmentsCapacity_019e043c-ca3f-7de7-823a-8b483430fcdd" xlink:href="trs-20260630.xsd#trs_IncrementalDebtCommitmentsCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_trs_IncrementalDebtCommitmentsCapacity_019e043c-ca3f-7de7-823a-8b483430fcdd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_NetLeverageRatio_019e043c-ca3f-7566-b282-58a56a9996be" xlink:href="trs-20260630.xsd#trs_NetLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_trs_NetLeverageRatio_019e043c-ca3f-7566-b282-58a56a9996be" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LetterOfCreditMaximumBorrowingCapacity_019e043c-ca3f-7e2e-b3d1-9a36a835c4b0" xlink:href="trs-20260630.xsd#trs_LetterOfCreditMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_trs_LetterOfCreditMaximumBorrowingCapacity_019e043c-ca3f-7e2e-b3d1-9a36a835c4b0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019e043c-ca3f-7026-920d-179e74cd3c68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_LineOfCredit_019e043c-ca3f-7026-920d-179e74cd3c68" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019e043c-ca3f-7f5c-9695-af4c189c8151" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019e043c-ca3f-7f5c-9695-af4c189c8151" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019e043c-ca3f-759f-b994-d0759d1dc262" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019e043c-ca3f-759f-b994-d0759d1dc262" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019e043c-ca3f-7140-9d8b-abf13facf609" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019e043c-ca3f-7140-9d8b-abf13facf609" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LongTermDebtFairValueOfParValue_019e043c-ca3f-7c03-8453-4e92ed338af9" xlink:href="trs-20260630.xsd#trs_LongTermDebtFairValueOfParValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_trs_LongTermDebtFairValueOfParValue_019e043c-ca3f-7c03-8453-4e92ed338af9" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LineOfCreditBorrowingCapacityConsideringCovenantRestrictions_019e043c-ca3f-77e8-87fa-4e393689a906" xlink:href="trs-20260630.xsd#trs_LineOfCreditBorrowingCapacityConsideringCovenantRestrictions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_trs_LineOfCreditBorrowingCapacityConsideringCovenantRestrictions_019e043c-ca3f-77e8-87fa-4e393689a906" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019e043c-ca3f-74d2-bdc6-12826acada2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDebtExtinguishmentCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_PaymentsOfDebtExtinguishmentCosts_019e043c-ca3f-74d2-bdc6-12826acada2c" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_019e043c-ca3f-7ee4-8e88-508c6b2cc7f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_019e043c-ca3f-7ee4-8e88-508c6b2cc7f8" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019e043c-ca3f-7cd8-b3e0-b539755db7ab" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ba4-a9c2-0c153e590a86" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_019e043c-ca3f-7cd8-b3e0-b539755db7ab" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtReceivablesFacilityDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#LongtermDebtReceivablesFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtReceivablesFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7db4-85c7-8e1a489cd9fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7db4-85c7-8e1a489cd9fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7e77-9d10-2dcc93c9dd50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7db4-85c7-8e1a489cd9fa" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7e77-9d10-2dcc93c9dd50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7e77-9d10-2dcc93c9dd50_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7e77-9d10-2dcc93c9dd50" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7e77-9d10-2dcc93c9dd50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-76ec-a94f-249f27428c9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7e77-9d10-2dcc93c9dd50" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-76ec-a94f-249f27428c9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019e043c-ca3f-7e51-874d-769e390abec6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-76ec-a94f-249f27428c9e" xlink:to="loc_us-gaap_SecuredDebtMember_019e043c-ca3f-7e51-874d-769e390abec6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SecuredDebtMaximumBorrowingCapacity_019e043c-ca3f-74b9-852d-3a0b58772432" xlink:href="trs-20260630.xsd#trs_SecuredDebtMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_trs_SecuredDebtMaximumBorrowingCapacity_019e043c-ca3f-74b9-852d-3a0b58772432" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e043c-ca3f-743d-9886-bbe173ce1772" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019e043c-ca3f-743d-9886-bbe173ce1772" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage_019e043c-ca3f-785a-a79e-05714c11cbae" xlink:href="trs-20260630.xsd#trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_trs_DebtInstrumentUnusedBorrowingCapacityFeePercentage_019e043c-ca3f-785a-a79e-05714c11cbae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_019e043c-ca3f-7612-add5-432157e77dc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SecuredDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_us-gaap_SecuredDebt_019e043c-ca3f-7612-add5-432157e77dc2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019e043c-ca3f-7f40-b037-e0f318f1c712" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount_019e043c-ca3f-7f40-b037-e0f318f1c712" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ReceivablesFacililtyDebtAggregateCosts_019e043c-ca3f-7da2-bc8c-62095e5694ea" xlink:href="trs-20260630.xsd#trs_ReceivablesFacililtyDebtAggregateCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_trs_ReceivablesFacililtyDebtAggregateCosts_019e043c-ca3f-7da2-bc8c-62095e5694ea" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentMaturityDate_019e043c-ca3f-779e-a888-607c9125f2f4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_us-gaap_DebtInstrumentMaturityDate_019e043c-ca3f-779e-a888-607c9125f2f4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AverageDiscountRateReceivablesFacility_019e043c-ca3f-7f59-9aa2-6f9cd789f46e" xlink:href="trs-20260630.xsd#trs_AverageDiscountRateReceivablesFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7ade-9685-1bc9e893a119" xlink:to="loc_trs_AverageDiscountRateReceivablesFacility_019e043c-ca3f-7f59-9aa2-6f9cd789f46e" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/OtherRevolvingLoanFacilityDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#OtherRevolvingLoanFacilityDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/OtherRevolvingLoanFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7928-9dee-eb071d81b176" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7278-ac65-c8bc5d64e7ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7928-9dee-eb071d81b176" xlink:to="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7278-ac65-c8bc5d64e7ed" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7774-bca3-c2088d583733" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7278-ac65-c8bc5d64e7ed" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7774-bca3-c2088d583733" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7774-bca3-c2088d583733_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7774-bca3-c2088d583733" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7774-bca3-c2088d583733_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7713-9354-3c304b414179" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019e043c-ca3f-7774-bca3-c2088d583733" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7713-9354-3c304b414179" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7a92-823c-5e2c82592858" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019e043c-ca3f-7713-9354-3c304b414179" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7a92-823c-5e2c82592858" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7fbc-b1f2-cdd2392facbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019e043c-ca3f-7278-ac65-c8bc5d64e7ed" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7fbc-b1f2-cdd2392facbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7fbc-b1f2-cdd2392facbf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7fbc-b1f2-cdd2392facbf" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7fbc-b1f2-cdd2392facbf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7466-af3a-3f359aebcf29" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7fbc-b1f2-cdd2392facbf" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7466-af3a-3f359aebcf29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_019e043c-ca3f-7358-92e5-23401c78d118" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7466-af3a-3f359aebcf29" xlink:to="loc_us-gaap_NonUsMember_019e043c-ca3f-7358-92e5-23401c78d118" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e043c-ca3f-7188-9eae-43d6229f07eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7928-9dee-eb071d81b176" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019e043c-ca3f-7188-9eae-43d6229f07eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019e043c-ca3f-77c8-b7be-edceaaf9344d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7928-9dee-eb071d81b176" xlink:to="loc_us-gaap_LineOfCredit_019e043c-ca3f-77c8-b7be-edceaaf9344d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/LongtermDebtFairValueDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#LongtermDebtFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/LongtermDebtFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7583-9b1a-bbbb35a3abfd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-7950-904c-53cc58acc9f0" xlink:href="trs-20260630.xsd#trs_ScheduleOfDebtInstrumentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7583-9b1a-bbbb35a3abfd" xlink:to="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-7950-904c-53cc58acc9f0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7335-9383-6d9958c1ad51" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-7950-904c-53cc58acc9f0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7335-9383-6d9958c1ad51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7335-9383-6d9958c1ad51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7335-9383-6d9958c1ad51" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7335-9383-6d9958c1ad51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7cf6-bf9e-e8bdc5168a4c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca3f-7335-9383-6d9958c1ad51" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7cf6-bf9e-e8bdc5168a4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca3f-7f44-a760-01d2ca42f90c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca3f-7cf6-bf9e-e8bdc5168a4c" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca3f-7f44-a760-01d2ca42f90c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7a34-823f-663f37ea8fb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-7950-904c-53cc58acc9f0" xlink:to="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7a34-823f-663f37ea8fb9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7a34-823f-663f37ea8fb9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7a34-823f-663f37ea8fb9" xlink:to="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7a34-823f-663f37ea8fb9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7206-8b49-996ebc8aaf40" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019e043c-ca3f-7a34-823f-663f37ea8fb9" xlink:to="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7206-8b49-996ebc8aaf40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7ab1-b43a-2f262bc8c3bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019e043c-ca3f-7206-8b49-996ebc8aaf40" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019e043c-ca3f-7ab1-b43a-2f262bc8c3bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-72dc-9213-f6e9ab205946" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_trs_ScheduleOfDebtInstrumentsTable_019e043c-ca3f-7950-904c-53cc58acc9f0" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-72dc-9213-f6e9ab205946" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-72dc-9213-f6e9ab205946_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-72dc-9213-f6e9ab205946" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-72dc-9213-f6e9ab205946_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7b1f-810b-93fdd9666a42" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-72dc-9213-f6e9ab205946" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7b1f-810b-93fdd9666a42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CreditAgreementMember_019e043c-ca3f-7407-9b32-58c18baca2e9" xlink:href="trs-20260630.xsd#trs_CreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7b1f-810b-93fdd9666a42" xlink:to="loc_trs_CreditAgreementMember_019e043c-ca3f-7407-9b32-58c18baca2e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019e043c-ca3f-73e1-a389-ff63b7ad5679" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7b1f-810b-93fdd9666a42" xlink:to="loc_us-gaap_SeniorNotesMember_019e043c-ca3f-73e1-a389-ff63b7ad5679" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019e043c-ca3f-782c-bfc8-b12b134678e1" xlink:href="trs-20260630.xsd#trs_A4.875SeniorUnsecuredNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7b1f-810b-93fdd9666a42" xlink:to="loc_trs_A4.875SeniorUnsecuredNotesDue2025Member_019e043c-ca3f-782c-bfc8-b12b134678e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019e043c-ca3f-738d-bdaf-305d1df810fa" xlink:href="trs-20260630.xsd#trs_A4125SeniorUnsecuredNotesDue2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7b1f-810b-93fdd9666a42" xlink:to="loc_trs_A4125SeniorUnsecuredNotesDue2029Member_019e043c-ca3f-738d-bdaf-305d1df810fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_019e043c-ca3f-74dc-b779-c3f08ff7f36c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7583-9b1a-bbbb35a3abfd" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_019e043c-ca3f-74dc-b779-c3f08ff7f36c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_019e043c-ca3f-71ee-b92a-11c2534f718b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019e043c-ca3f-7583-9b1a-bbbb35a3abfd" xlink:to="loc_us-gaap_LongTermDebtFairValue_019e043c-ca3f-71ee-b92a-11c2534f718b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativeNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDerivativeNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativeNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-72f4-bba9-53d45ee05b57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-72f4-bba9-53d45ee05b57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-72f4-bba9-53d45ee05b57_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-72f4-bba9-53d45ee05b57" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-72f4-bba9-53d45ee05b57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7198-af2b-c3fec73d3341" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-72f4-bba9-53d45ee05b57" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7198-af2b-c3fec73d3341" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7314-b9da-6def42366271" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7198-af2b-c3fec73d3341" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7314-b9da-6def42366271" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019e043c-ca3f-70ce-bd90-37190d3eac7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7198-af2b-c3fec73d3341" xlink:to="loc_us-gaap_NondesignatedMember_019e043c-ca3f-70ce-bd90-37190d3eac7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca3f-737f-955a-80a32e73383b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:to="loc_srt_RangeAxis_019e043c-ca3f-737f-955a-80a32e73383b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca3f-737f-955a-80a32e73383b_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca3f-737f-955a-80a32e73383b" xlink:to="loc_srt_RangeMember_019e043c-ca3f-737f-955a-80a32e73383b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca3f-7a03-a40a-c691c3bb5ac6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca3f-737f-955a-80a32e73383b" xlink:to="loc_srt_RangeMember_019e043c-ca3f-7a03-a40a-c691c3bb5ac6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca3f-739b-8c1a-6caa6d89817a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca3f-7a03-a40a-c691c3bb5ac6" xlink:to="loc_srt_MaximumMember_019e043c-ca3f-739b-8c1a-6caa6d89817a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca3f-7372-86f1-f3461496150f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca3f-7a03-a40a-c691c3bb5ac6" xlink:to="loc_srt_MinimumMember_019e043c-ca3f-7372-86f1-f3461496150f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7207-afb9-91088bcb7d32" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:to="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7207-afb9-91088bcb7d32" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7207-afb9-91088bcb7d32_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7207-afb9-91088bcb7d32" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-7207-afb9-91088bcb7d32_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-71c9-a2d7-a6592212ef74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019e043c-ca3f-7207-afb9-91088bcb7d32" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-71c9-a2d7-a6592212ef74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SeniorSecuredTermLoanMember_019e043c-ca3f-7568-8827-5871db3b56d5" xlink:href="trs-20260630.xsd#trs_SeniorSecuredTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019e043c-ca3f-71c9-a2d7-a6592212ef74" xlink:to="loc_trs_SeniorSecuredTermLoanMember_019e043c-ca3f-7568-8827-5871db3b56d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-78d4-9e94-c17147eb2151" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-78d4-9e94-c17147eb2151" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-78d4-9e94-c17147eb2151_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-78d4-9e94-c17147eb2151" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-78d4-9e94-c17147eb2151_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-706f-8824-73c1a1e7ddf5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-78d4-9e94-c17147eb2151" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-706f-8824-73c1a1e7ddf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7036-be7a-79c1cac73708" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-706f-8824-73c1a1e7ddf5" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7036-be7a-79c1cac73708" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019e043c-ca3f-7f42-b8f2-c0eac2615dde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-706f-8824-73c1a1e7ddf5" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019e043c-ca3f-7f42-b8f2-c0eac2615dde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019e043c-ca3f-727e-97ba-37714e77d05f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-706f-8824-73c1a1e7ddf5" xlink:to="loc_us-gaap_InterestRateSwapMember_019e043c-ca3f-727e-97ba-37714e77d05f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-7a14-af56-726b4f173bd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-7a14-af56-726b4f173bd1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7a14-af56-726b4f173bd1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-7a14-af56-726b4f173bd1" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7a14-af56-726b4f173bd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-711c-acfb-2c20ab0b38cc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-7a14-af56-726b4f173bd1" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-711c-acfb-2c20ab0b38cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-72aa-b838-e97ecba660d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-711c-acfb-2c20ab0b38cc" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-72aa-b838-e97ecba660d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019e043c-ca3f-7274-910a-b5a1d51545cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-711c-acfb-2c20ab0b38cc" xlink:to="loc_us-gaap_CashFlowHedgingMember_019e043c-ca3f-7274-910a-b5a1d51545cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeContractDateAxis_019e043c-ca3f-7411-90f5-f1890c78c4e5" xlink:href="trs-20260630.xsd#trs_DerivativeContractDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7b8e-806e-6feedb28d6b4" xlink:to="loc_trs_DerivativeContractDateAxis_019e043c-ca3f-7411-90f5-f1890c78c4e5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7411-90f5-f1890c78c4e5_default" xlink:href="trs-20260630.xsd#trs_DerivativeMaturityDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DerivativeContractDateAxis_019e043c-ca3f-7411-90f5-f1890c78c4e5" xlink:to="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7411-90f5-f1890c78c4e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7a7c-b12f-24854b135341" xlink:href="trs-20260630.xsd#trs_DerivativeMaturityDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DerivativeContractDateAxis_019e043c-ca3f-7411-90f5-f1890c78c4e5" xlink:to="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7a7c-b12f-24854b135341" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeJune2020MaturityMember_019e043c-ca3f-7207-9371-43747b6144c7" xlink:href="trs-20260630.xsd#trs_DerivativeJune2020MaturityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7a7c-b12f-24854b135341" xlink:to="loc_trs_DerivativeJune2020MaturityMember_019e043c-ca3f-7207-9371-43747b6144c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_June2024DerivativeDomain_019e043c-ca3f-7a79-ac62-0cb6b9ff7141" xlink:href="trs-20260630.xsd#trs_June2024DerivativeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7a7c-b12f-24854b135341" xlink:to="loc_trs_June2024DerivativeDomain_019e043c-ca3f-7a79-ac62-0cb6b9ff7141" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeApril2029MaturityDomain_019e043c-ca3f-7e5c-afc9-7b7a74b89966" xlink:href="trs-20260630.xsd#trs_DerivativeApril2029MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7a7c-b12f-24854b135341" xlink:to="loc_trs_DerivativeApril2029MaturityDomain_019e043c-ca3f-7e5c-afc9-7b7a74b89966" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeApril2024MaturityDomain_019e043c-ca3f-7850-8db6-0b31e6692a53" xlink:href="trs-20260630.xsd#trs_DerivativeApril2024MaturityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeMaturityDateDomain_019e043c-ca3f-7a7c-b12f-24854b135341" xlink:to="loc_trs_DerivativeApril2024MaturityDomain_019e043c-ca3f-7850-8db6-0b31e6692a53" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeContractDateDomain_019e043c-ca3f-7cc0-b14d-9ab60ebcb07f" xlink:href="trs-20260630.xsd#trs_DerivativeContractDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DerivativeContractDateAxis_019e043c-ca3f-7411-90f5-f1890c78c4e5" xlink:to="loc_trs_DerivativeContractDateDomain_019e043c-ca3f-7cc0-b14d-9ab60ebcb07f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_February2024DerivativeContractDateDomain_019e043c-ca3f-7a8f-b2ee-c64ea172e56b" xlink:href="trs-20260630.xsd#trs_February2024DerivativeContractDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DerivativeContractDateDomain_019e043c-ca3f-7cc0-b14d-9ab60ebcb07f" xlink:to="loc_trs_February2024DerivativeContractDateDomain_019e043c-ca3f-7a8f-b2ee-c64ea172e56b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019e043c-ca3f-780d-8047-fe13d31266e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_019e043c-ca3f-780d-8047-fe13d31266e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_019e043c-ca3f-7023-9b56-a3fd17b678ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_MaximumRemainingMaturityOfForeignCurrencyDerivatives1_019e043c-ca3f-7023-9b56-a3fd17b678ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_019e043c-ca3f-7ecc-b639-a9fbfaef558d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_019e043c-ca3f-7ecc-b639-a9fbfaef558d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeCashReceivedOnHedge_019e043c-ca3f-7a97-97e8-38fe8cd3b68e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeCashReceivedOnHedge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_DerivativeCashReceivedOnHedge_019e043c-ca3f-7a97-97e8-38fe8cd3b68e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e043c-ca3f-75cd-97de-dca0cc8f1b6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e043c-ca3f-75cd-97de-dca0cc8f1b6f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeMaturityDates_019e043c-ca3f-72be-b07f-7e00590ccc0a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeMaturityDates"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_DerivativeMaturityDates_019e043c-ca3f-72be-b07f-7e00590ccc0a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Cashpaidatterminationofinterestrateswap_019e043c-ca3f-7967-8478-f0d2c410f8ff" xlink:href="trs-20260630.xsd#trs_Cashpaidatterminationofinterestrateswap"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_trs_Cashpaidatterminationofinterestrateswap_019e043c-ca3f-7967-8478-f0d2c410f8ff" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_019e043c-ca3f-73ca-8775-fab471c48323" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7481-b935-22a02e9fda09" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_019e043c-ca3f-73ca-8775-fab471c48323" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-70a4-b675-fad4a762b044_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-70a4-b675-fad4a762b044_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7dbd-8294-74763adb43a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7dbd-8294-74763adb43a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-7b87-affc-8901ec3ebe48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7dbd-8294-74763adb43a4" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-7b87-affc-8901ec3ebe48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-74ed-bd61-e8d4f662e711_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-74ed-bd61-e8d4f662e711_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7110-b2cc-f20bafa89509" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7110-b2cc-f20bafa89509" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7384-904f-9f83915ea590" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7110-b2cc-f20bafa89509" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7384-904f-9f83915ea590" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7326-90a8-bd750fdf70e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7326-90a8-bd750fdf70e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7f3d-a073-9294fd88e7d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7326-90a8-bd750fdf70e4" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7f3d-a073-9294fd88e7d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e043c-ca3f-7ed6-80b3-6094d396a4c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e043c-ca3f-7ed6-80b3-6094d396a4c1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e043c-ca3f-78a5-96b7-5ced70d44cd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e043c-ca3f-78a5-96b7-5ced70d44cd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e043c-ca3f-76f7-800e-15a193b9b7ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e043c-ca3f-76f7-800e-15a193b9b7ff" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPositionDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-70a4-b675-fad4a762b044_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-70a4-b675-fad4a762b044_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7dbd-8294-74763adb43a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-70a4-b675-fad4a762b044" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7dbd-8294-74763adb43a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-7b87-affc-8901ec3ebe48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7dbd-8294-74763adb43a4" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-7b87-affc-8901ec3ebe48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-74ed-bd61-e8d4f662e711_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-74ed-bd61-e8d4f662e711_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7110-b2cc-f20bafa89509" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74ed-bd61-e8d4f662e711" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7110-b2cc-f20bafa89509" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7384-904f-9f83915ea590" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7110-b2cc-f20bafa89509" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7384-904f-9f83915ea590" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019e043c-ca3f-7700-ba4b-76aeca5a5621" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7326-90a8-bd750fdf70e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-75b6-b1b6-2a4ab6bbf681" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7326-90a8-bd750fdf70e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7f3d-a073-9294fd88e7d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7326-90a8-bd750fdf70e4" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7f3d-a073-9294fd88e7d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e043c-ca3f-78a5-96b7-5ced70d44cd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_019e043c-ca3f-78a5-96b7-5ced70d44cd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e043c-ca3f-76f7-800e-15a193b9b7ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019e043c-ca3f-75c3-b85e-809ad8e0bc2e" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_019e043c-ca3f-76f7-800e-15a193b9b7ff" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-7ed7-8515-63ea30748bf7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-7ed7-8515-63ea30748bf7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e41a7-2135-7524-a60c-0086950cc203" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e41a7-2135-7524-a60c-0086950cc203" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_2" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_2"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_2" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e41a7-2135-7524-a60c-0086950cc203" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfFinancialPositionLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019e41a7-2135-7524-a60c-0086950cc203" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_3" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_3"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceDetails_3" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-710c-8893-fe1423a84b74_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca3f-710c-8893-fe1423a84b74" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca3f-7f73-9244-f111efa479a5" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca3f-735a-9821-1432d1ea9cb9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7678-8ee1-1236d279cbc6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7678-8ee1-1236d279cbc6" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7804-a950-c99bea6296bb" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-7a22-a78f-e2beb3bef861" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7f2b-8315-87a67a80c6aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7f2b-8315-87a67a80c6aa" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7dfa-9cd9-2793657150a4" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-7ac4-adf9-5a15ea06398d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-7ed7-8515-63ea30748bf7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7e15-9a9f-79e6d4383f87" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-7ed7-8515-63ea30748bf7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e043c-ca3f-7d8b-a225-9fa1ba4b253f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-711f-a2d7-e57ea4a12143" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca3f-705d-bbd8-2d0fb7a7183d" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-7047-8533-0206901cd522" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca3f-7047-8533-0206901cd522" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7ddc-bdee-d44bd1dcdb82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7ddc-bdee-d44bd1dcdb82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7ebe-99be-3344ba6e0e8d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7ebe-99be-3344ba6e0e8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-77ac-83e8-8c001ccae5c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-77ac-83e8-8c001ccae5c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-73bf-af8c-f5071fe3188d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-77ac-83e8-8c001ccae5c2" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-73bf-af8c-f5071fe3188d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_019e043c-ca3f-72cd-ade6-74c07301431f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_019e043c-ca3f-72cd-ade6-74c07301431f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019e043c-ca3f-7520-a916-0518a4e9a168" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019e043c-ca3f-7520-a916-0518a4e9a168" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDesignatedashedgingFinancialPerformanceNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7ddc-bdee-d44bd1dcdb82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-713f-8fcc-7ab8c6c44b2d" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7ddc-bdee-d44bd1dcdb82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019e043c-ca3f-7c74-9d9e-2c4f487d3751" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7ebe-99be-3344ba6e0e8d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7ebe-99be-3344ba6e0e8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-77ac-83e8-8c001ccae5c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7ebe-99be-3344ba6e0e8d" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-77ac-83e8-8c001ccae5c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-73bf-af8c-f5071fe3188d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-77ac-83e8-8c001ccae5c2" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019e043c-ca3f-73bf-af8c-f5071fe3188d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_019e043c-ca3f-72cd-ade6-74c07301431f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimateOfTimeToTransfer1_019e043c-ca3f-72cd-ade6-74c07301431f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019e043c-ca3f-7520-a916-0518a4e9a168" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019e043c-ca3f-7fb0-a020-b8ac55386d68" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred_019e043c-ca3f-7520-a916-0518a4e9a168" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativesnotdesignatedashedginginstrumentsDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsDerivativesnotdesignatedashedginginstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsDerivativesnotdesignatedashedginginstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7b51-91cf-35ae8f7c7ce7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019e043c-ca3f-7f48-8515-8dfe06f22aa8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7b51-91cf-35ae8f7c7ce7" xlink:to="loc_us-gaap_DerivativeTable_019e043c-ca3f-7f48-8515-8dfe06f22aa8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7a04-a36a-424aa5774d31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7f48-8515-8dfe06f22aa8" xlink:to="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7a04-a36a-424aa5774d31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7a04-a36a-424aa5774d31_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7a04-a36a-424aa5774d31" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7a04-a36a-424aa5774d31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7817-b827-e70896b7067b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019e043c-ca3f-7a04-a36a-424aa5774d31" xlink:to="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7817-b827-e70896b7067b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019e043c-ca3f-7fd2-91d0-bb45999f33a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019e043c-ca3f-7817-b827-e70896b7067b" xlink:to="loc_us-gaap_NondesignatedMember_019e043c-ca3f-7fd2-91d0-bb45999f33a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7985-8757-e7cb68b3fca7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019e043c-ca3f-7f48-8515-8dfe06f22aa8" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7985-8757-e7cb68b3fca7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7985-8757-e7cb68b3fca7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7985-8757-e7cb68b3fca7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-7985-8757-e7cb68b3fca7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-738b-83bf-20251bb186b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-7985-8757-e7cb68b3fca7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-738b-83bf-20251bb186b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019e043c-ca3f-7bce-a0ae-ac619ec02095" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-738b-83bf-20251bb186b0" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019e043c-ca3f-7bce-a0ae-ac619ec02095" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrencySwapMember_019e043c-ca3f-78ce-9392-3d751f87fca1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CurrencySwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-738b-83bf-20251bb186b0" xlink:to="loc_us-gaap_CurrencySwapMember_019e043c-ca3f-78ce-9392-3d751f87fca1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e043c-ca3f-755a-a555-8920088f9a81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7b51-91cf-35ae8f7c7ce7" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e043c-ca3f-755a-a555-8920088f9a81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet_019e043c-ca3f-7c49-9d34-733f2f24e1bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019e043c-ca3f-7b51-91cf-35ae8f7c7ce7" xlink:to="loc_us-gaap_GainLossOnForeignCurrencyDerivativesRecordedInEarningsNet_019e043c-ca3f-7c49-9d34-733f2f24e1bd" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DerivativeInstrumentsFairValueMeasurementsDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DerivativeInstrumentsFairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DerivativeInstrumentsFairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e043c-ca40-71c4-adb6-87e4ec53d4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e043c-ca3f-765a-8404-f329bd7c4bc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e043c-ca40-71c4-adb6-87e4ec53d4e8" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e043c-ca3f-765a-8404-f329bd7c4bc9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019e043c-ca3f-7e9a-946f-2c2fd9147891" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e043c-ca3f-765a-8404-f329bd7c4bc9" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019e043c-ca3f-7e9a-946f-2c2fd9147891" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e043c-ca3f-7e9a-946f-2c2fd9147891_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e043c-ca3f-7e9a-946f-2c2fd9147891" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e043c-ca3f-7e9a-946f-2c2fd9147891_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e043c-ca3f-7314-b58c-b51b1ead9946" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019e043c-ca3f-7e9a-946f-2c2fd9147891" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e043c-ca3f-7314-b58c-b51b1ead9946" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-725c-8e75-02fcf5298092" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019e043c-ca3f-7314-b58c-b51b1ead9946" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca3f-725c-8e75-02fcf5298092" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74bf-8dc1-405713538ce9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e043c-ca3f-765a-8404-f329bd7c4bc9" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74bf-8dc1-405713538ce9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-74bf-8dc1-405713538ce9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74bf-8dc1-405713538ce9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca3f-74bf-8dc1-405713538ce9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-7eb9-9137-95eeed7e8340" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca3f-74bf-8dc1-405713538ce9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-7eb9-9137-95eeed7e8340" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca40-7520-85c8-137e6c4b7caf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-7eb9-9137-95eeed7e8340" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca40-7520-85c8-137e6c4b7caf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019e043c-ca40-71cf-9dad-12ef63034bf0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-7eb9-9137-95eeed7e8340" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019e043c-ca40-71cf-9dad-12ef63034bf0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca40-7a18-89f3-8e25663491c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e043c-ca3f-765a-8404-f329bd7c4bc9" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca40-7a18-89f3-8e25663491c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca40-7a18-89f3-8e25663491c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca40-7a18-89f3-8e25663491c1" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca40-7a18-89f3-8e25663491c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca40-7038-9fd9-41e7734584b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-ca40-7a18-89f3-8e25663491c1" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca40-7038-9fd9-41e7734584b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca40-72a9-9beb-2939c73a2358" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-ca40-7038-9fd9-41e7734584b3" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-ca40-72a9-9beb-2939c73a2358" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e043c-ca40-7bb8-9d8a-7798f84da8a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e043c-ca3f-765a-8404-f329bd7c4bc9" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e043c-ca40-7bb8-9d8a-7798f84da8a6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e043c-ca40-7bb8-9d8a-7798f84da8a6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e043c-ca40-7bb8-9d8a-7798f84da8a6" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e043c-ca40-7bb8-9d8a-7798f84da8a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e043c-ca40-794b-bac5-27b6aec1963c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_019e043c-ca40-7bb8-9d8a-7798f84da8a6" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e043c-ca40-794b-bac5-27b6aec1963c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_019e043c-ca40-7d89-9c5b-c791180b4cdc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_019e043c-ca40-794b-bac5-27b6aec1963c" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_019e043c-ca40-7d89-9c5b-c791180b4cdc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca40-76f8-af12-9c4f0b06aef4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019e043c-ca3f-765a-8404-f329bd7c4bc9" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca40-76f8-af12-9c4f0b06aef4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca40-76f8-af12-9c4f0b06aef4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca40-76f8-af12-9c4f0b06aef4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca40-76f8-af12-9c4f0b06aef4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca40-75cb-b631-fdece712fe21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019e043c-ca40-76f8-af12-9c4f0b06aef4" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca40-75cb-b631-fdece712fe21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019e043c-ca40-78bf-beaa-d36a0e6145ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca40-75cb-b631-fdece712fe21" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019e043c-ca40-78bf-beaa-d36a0e6145ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca40-7bbf-88f5-7a8010abf63e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca40-75cb-b631-fdece712fe21" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019e043c-ca40-7bbf-88f5-7a8010abf63e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019e043c-ca40-7ede-8a6e-22883d9eb5b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019e043c-ca40-75cb-b631-fdece712fe21" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019e043c-ca40-7ede-8a6e-22883d9eb5b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesAtFairValueNet_019e043c-ca40-71df-be76-37a68019bca3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsInHedgesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e043c-ca40-71c4-adb6-87e4ec53d4e8" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesAtFairValueNet_019e043c-ca40-71df-be76-37a68019bca3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsAtFairValueNet_019e043c-ca40-7c0e-97e2-0b59d9f8d428" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019e043c-ca40-71c4-adb6-87e4ec53d4e8" xlink:to="loc_us-gaap_OtherDerivativesNotDesignatedAsHedgingInstrumentsAtFairValueNet_019e043c-ca40-7c0e-97e2-0b59d9f8d428" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesAsbestosNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-7284-b723-33d49691ba70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-7284-b723-33d49691ba70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-715c-a305-8d5bf19f7fc7_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:to="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-715c-a305-8d5bf19f7fc7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-7043-802f-debb1919a8a4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:to="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-7043-802f-debb1919a8a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7dfb-83c3-e4a90657efe9_default" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:to="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7dfb-83c3-e4a90657efe9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:to="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PunitiveOnlyDamagesMember_019e043c-ca40-799b-b0db-cf98e5009051" xlink:href="trs-20260630.xsd#trs_PunitiveOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:to="loc_trs_PunitiveOnlyDamagesMember_019e043c-ca40-799b-b0db-cf98e5009051" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CompensatoryOnlyDamagesMember_019e043c-ca40-778d-8d37-c5192724650b" xlink:href="trs-20260630.xsd#trs_CompensatoryOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:to="loc_trs_CompensatoryOnlyDamagesMember_019e043c-ca40-778d-8d37-c5192724650b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74eb-ac69-a3f9699ca6ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74eb-ac69-a3f9699ca6ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-72f6-9c60-97aa26a6a787" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:to="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-72f6-9c60-97aa26a6a787" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-7f53-8e69-2d17124910e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnvironmentalIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:to="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-7f53-8e69-2d17124910e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7e3e-b4f3-799127368e50_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7e3e-b4f3-799127368e50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7edb-92ac-a82b91624662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7edb-92ac-a82b91624662" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019e043c-ca40-78e5-9a1c-ed0e49922b50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7edb-92ac-a82b91624662" xlink:to="loc_us-gaap_PendingLitigationMember_019e043c-ca40-78e5-9a1c-ed0e49922b50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7943-9f28-24633b90c24a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:to="loc_srt_RangeMember_019e043c-ca40-7943-9f28-24633b90c24a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:to="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca40-717b-9472-f78ac458b3e9" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:to="loc_srt_MinimumMember_019e043c-ca40-717b-9472-f78ac458b3e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca40-7589-bfe7-58a44b57a491" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:to="loc_srt_MaximumMember_019e043c-ca40-7589-bfe7-58a44b57a491" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations_019e043c-ca40-713b-bde2-8e79cfcea22f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations_019e043c-ca40-713b-bde2-8e79cfcea22f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_019e043c-ca40-7a3d-87ab-46132073cb3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_019e043c-ca40-7a3d-87ab-46132073cb3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyPendingCasesNumber_019e043c-ca40-70ae-8221-aa0e4ce31ff1" xlink:href="trs-20260630.xsd#trs_LossContingencyPendingCasesNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_LossContingencyPendingCasesNumber_019e043c-ca40-70ae-8221-aa0e4ce31ff1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_019e043c-ca40-72e2-ab0c-df690c9ab07d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_019e043c-ca40-72e2-ab0c-df690c9ab07d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019e043c-ca40-703b-8c37-6fef4f59eef8" xlink:href="trs-20260630.xsd#trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019e043c-ca40-703b-8c37-6fef4f59eef8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_019e043c-ca40-71e8-8199-08109e23e785" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LitigationSettlementExpense_019e043c-ca40-71e8-8199-08109e23e785" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019e043c-ca40-7360-b854-8ef890e289b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019e043c-ca40-7360-b854-8ef890e289b7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_019e043c-ca40-71ea-8451-4f511065bf3b" xlink:href="trs-20260630.xsd#trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_019e043c-ca40-71ea-8451-4f511065bf3b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LegalFees_019e043c-ca40-7afa-addd-85e25dfdf3c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LegalFees_019e043c-ca40-7afa-addd-85e25dfdf3c3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Impactofchangeinaccountingprinciple_019e043c-ca40-784b-bf20-d3d62ea8651d" xlink:href="trs-20260630.xsd#trs_Impactofchangeinaccountingprinciple"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_Impactofchangeinaccountingprinciple_019e043c-ca40-784b-bf20-d3d62ea8651d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-74c6-ac17-62d809e8fb8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-74c6-ac17-62d809e8fb8f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019e043c-ca40-75de-9510-a517d1a39b98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019e043c-ca40-75de-9510-a517d1a39b98" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosNarrativeDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesAsbestosNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-715c-a305-8d5bf19f7fc7_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:to="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-715c-a305-8d5bf19f7fc7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-7043-802f-debb1919a8a4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019e043c-ca40-715c-a305-8d5bf19f7fc7" xlink:to="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-7043-802f-debb1919a8a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7dfb-83c3-e4a90657efe9_default" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:to="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7dfb-83c3-e4a90657efe9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7dfb-83c3-e4a90657efe9" xlink:to="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PunitiveOnlyDamagesMember_019e043c-ca40-799b-b0db-cf98e5009051" xlink:href="trs-20260630.xsd#trs_PunitiveOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:to="loc_trs_PunitiveOnlyDamagesMember_019e043c-ca40-799b-b0db-cf98e5009051" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CompensatoryOnlyDamagesMember_019e043c-ca40-778d-8d37-c5192724650b" xlink:href="trs-20260630.xsd#trs_CompensatoryOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7607-b0c7-bea0140a0c1c" xlink:to="loc_trs_CompensatoryOnlyDamagesMember_019e043c-ca40-778d-8d37-c5192724650b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74eb-ac69-a3f9699ca6ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74eb-ac69-a3f9699ca6ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74eb-ac69-a3f9699ca6ca" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-72f6-9c60-97aa26a6a787" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:to="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-72f6-9c60-97aa26a6a787" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-7f53-8e69-2d17124910e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnvironmentalIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7538-a01c-efbe3c13c5d2" xlink:to="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-7f53-8e69-2d17124910e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7e3e-b4f3-799127368e50_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7e3e-b4f3-799127368e50_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7edb-92ac-a82b91624662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7e3e-b4f3-799127368e50" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7edb-92ac-a82b91624662" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019e043c-ca40-78e5-9a1c-ed0e49922b50" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7edb-92ac-a82b91624662" xlink:to="loc_us-gaap_PendingLitigationMember_019e043c-ca40-78e5-9a1c-ed0e49922b50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-740e-95db-df5f78828257" xlink:to="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7943-9f28-24633b90c24a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:to="loc_srt_RangeMember_019e043c-ca40-7943-9f28-24633b90c24a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7943-9f28-24633b90c24a" xlink:to="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca40-717b-9472-f78ac458b3e9" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:to="loc_srt_MinimumMember_019e043c-ca40-717b-9472-f78ac458b3e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca40-7589-bfe7-58a44b57a491" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7c24-808f-52ed219871a1" xlink:to="loc_srt_MaximumMember_019e043c-ca40-7589-bfe7-58a44b57a491" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations_019e043c-ca40-713b-bde2-8e79cfcea22f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LiabilitiesSubjectToCompromiseAsbestosObligations_019e043c-ca40-713b-bde2-8e79cfcea22f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_019e043c-ca40-7a3d-87ab-46132073cb3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_019e043c-ca40-7a3d-87ab-46132073cb3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyPendingCasesNumber_019e043c-ca40-70ae-8221-aa0e4ce31ff1" xlink:href="trs-20260630.xsd#trs_LossContingencyPendingCasesNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_LossContingencyPendingCasesNumber_019e043c-ca40-70ae-8221-aa0e4ce31ff1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_019e043c-ca40-72e2-ab0c-df690c9ab07d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_019e043c-ca40-72e2-ab0c-df690c9ab07d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019e043c-ca40-703b-8c37-6fef4f59eef8" xlink:href="trs-20260630.xsd#trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019e043c-ca40-703b-8c37-6fef4f59eef8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_019e043c-ca40-71e8-8199-08109e23e785" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LitigationSettlementExpense_019e043c-ca40-71e8-8199-08109e23e785" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019e043c-ca40-7360-b854-8ef890e289b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019e043c-ca40-7360-b854-8ef890e289b7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_019e043c-ca40-71ea-8451-4f511065bf3b" xlink:href="trs-20260630.xsd#trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_PercentageOfSettlementAndDefenseCostsCoveredByInsurance_019e043c-ca40-71ea-8451-4f511065bf3b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LegalFees_019e043c-ca40-7afa-addd-85e25dfdf3c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LegalFees_019e043c-ca40-7afa-addd-85e25dfdf3c3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Impactofchangeinaccountingprinciple_019e043c-ca40-784b-bf20-d3d62ea8651d" xlink:href="trs-20260630.xsd#trs_Impactofchangeinaccountingprinciple"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_trs_Impactofchangeinaccountingprinciple_019e043c-ca40-784b-bf20-d3d62ea8651d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-74c6-ac17-62d809e8fb8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-74c6-ac17-62d809e8fb8f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019e043c-ca40-75de-9510-a517d1a39b98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7d9b-a231-d79add8b38b4" xlink:to="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019e043c-ca40-75de-9510-a517d1a39b98" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosClaimantandSettlementDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesAsbestosClaimantandSettlementDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosClaimantandSettlementDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-73e2-8092-3d9d4c7c6e66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-73e2-8092-3d9d4c7c6e66" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7a9b-8470-f13672f0cae1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-73e2-8092-3d9d4c7c6e66" xlink:to="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7a9b-8470-f13672f0cae1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7a9b-8470-f13672f0cae1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7a9b-8470-f13672f0cae1" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7a9b-8470-f13672f0cae1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7189-8216-e8511f9c2b68" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7a9b-8470-f13672f0cae1" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7189-8216-e8511f9c2b68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019e043c-ca40-741b-b848-fda0b05a5107" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7189-8216-e8511f9c2b68" xlink:to="loc_us-gaap_PendingLitigationMember_019e043c-ca40-741b-b848-fda0b05a5107" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7bb7-a11f-0bf7ea9ea198" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-73e2-8092-3d9d4c7c6e66" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7bb7-a11f-0bf7ea9ea198" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7bb7-a11f-0bf7ea9ea198_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7bb7-a11f-0bf7ea9ea198" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7bb7-a11f-0bf7ea9ea198_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-798f-9118-6d82b5f868cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7bb7-a11f-0bf7ea9ea198" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-798f-9118-6d82b5f868cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-72ae-82a7-82a0f475b591" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-798f-9118-6d82b5f868cf" xlink:to="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-72ae-82a7-82a0f475b591" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_019e043c-ca40-764e-89ff-b5e97c4136e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_019e043c-ca40-764e-89ff-b5e97c4136e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019e043c-ca40-718d-b329-d393e39af7b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNewClaimsFiledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:to="loc_us-gaap_LossContingencyNewClaimsFiledNumber_019e043c-ca40-718d-b329-d393e39af7b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyClaimsDismissedNumber_019e043c-ca40-7b35-a98c-c9fdfa12ddb1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyClaimsDismissedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:to="loc_us-gaap_LossContingencyClaimsDismissedNumber_019e043c-ca40-7b35-a98c-c9fdfa12ddb1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyClaimsSettledNumber_019e043c-ca40-79bf-9daf-3b9a07243a2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyClaimsSettledNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:to="loc_us-gaap_LossContingencyClaimsSettledNumber_019e043c-ca40-79bf-9daf-3b9a07243a2f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencySettlementAgreementAverageConsideration_019e043c-ca40-7b46-b9c3-d163d9aae4ad" xlink:href="trs-20260630.xsd#trs_LossContingencySettlementAgreementAverageConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:to="loc_trs_LossContingencySettlementAgreementAverageConsideration_019e043c-ca40-7b46-b9c3-d163d9aae4ad" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LegalFees_019e043c-ca40-755d-a70f-235620eb9200" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-71cf-adab-bac127afa22e" xlink:to="loc_us-gaap_LegalFees_019e043c-ca40-755d-a70f-235620eb9200" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosDamagesSoughtDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesAsbestosDamagesSoughtDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesAsbestosDamagesSoughtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7fcf-822d-b38536aa5fc7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7bbd-9800-75c4cb1ada70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7fcf-822d-b38536aa5fc7" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7bbd-9800-75c4cb1ada70" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-78c9-b20a-431011400b94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7bbd-9800-75c4cb1ada70" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-78c9-b20a-431011400b94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-78c9-b20a-431011400b94_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-78c9-b20a-431011400b94" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-78c9-b20a-431011400b94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7789-8d0d-dfb75a85202b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-78c9-b20a-431011400b94" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7789-8d0d-dfb75a85202b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-746b-8f46-465f665bb76a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7789-8d0d-dfb75a85202b" xlink:to="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-746b-8f46-465f665bb76a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-76e2-ab69-993aed0f843d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7bbd-9800-75c4cb1ada70" xlink:to="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-76e2-ab69-993aed0f843d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-76e2-ab69-993aed0f843d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-76e2-ab69-993aed0f843d" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-76e2-ab69-993aed0f843d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-72ec-8b1d-060f73215433" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-76e2-ab69-993aed0f843d" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-72ec-8b1d-060f73215433" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PendingLitigationMember_019e043c-ca40-7333-b279-a1a66991d6a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PendingLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-72ec-8b1d-060f73215433" xlink:to="loc_us-gaap_PendingLitigationMember_019e043c-ca40-7333-b279-a1a66991d6a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7e9b-94cd-0208494fb0a8" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7bbd-9800-75c4cb1ada70" xlink:to="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7e9b-94cd-0208494fb0a8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7e9b-94cd-0208494fb0a8_default" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7e9b-94cd-0208494fb0a8" xlink:to="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-7e9b-94cd-0208494fb0a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-75a3-a397-d1cfb88192c9" xlink:href="trs-20260630.xsd#trs_DamagesSoughtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtTypeAxis_019e043c-ca40-7e9b-94cd-0208494fb0a8" xlink:to="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-75a3-a397-d1cfb88192c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CompensatoryOnlyDamagesMember_019e043c-ca40-701b-a474-4d4d17d620eb" xlink:href="trs-20260630.xsd#trs_CompensatoryOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-75a3-a397-d1cfb88192c9" xlink:to="loc_trs_CompensatoryOnlyDamagesMember_019e043c-ca40-701b-a474-4d4d17d620eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PunitiveOnlyDamagesMember_019e043c-ca40-77a6-87d4-5c1e3b520007" xlink:href="trs-20260630.xsd#trs_PunitiveOnlyDamagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtTypeDomain_019e043c-ca40-75a3-a397-d1cfb88192c9" xlink:to="loc_trs_PunitiveOnlyDamagesMember_019e043c-ca40-77a6-87d4-5c1e3b520007" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtRangeAxis_019e043c-ca40-7150-9d68-34361e894c33" xlink:href="trs-20260630.xsd#trs_DamagesSoughtRangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7bbd-9800-75c4cb1ada70" xlink:to="loc_trs_DamagesSoughtRangeAxis_019e043c-ca40-7150-9d68-34361e894c33" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtDomain_019e043c-ca40-7150-9d68-34361e894c33_default" xlink:href="trs-20260630.xsd#trs_DamagesSoughtDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DamagesSoughtRangeAxis_019e043c-ca40-7150-9d68-34361e894c33" xlink:to="loc_trs_DamagesSoughtDomain_019e043c-ca40-7150-9d68-34361e894c33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtDomain_019e043c-ca40-7bcd-98a4-3ef448cc675f" xlink:href="trs-20260630.xsd#trs_DamagesSoughtDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtRangeAxis_019e043c-ca40-7150-9d68-34361e894c33" xlink:to="loc_trs_DamagesSoughtDomain_019e043c-ca40-7bcd-98a4-3ef448cc675f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Range1Member_019e043c-ca40-7e96-94ec-1cb817ace42b" xlink:href="trs-20260630.xsd#trs_Range1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_019e043c-ca40-7bcd-98a4-3ef448cc675f" xlink:to="loc_trs_Range1Member_019e043c-ca40-7e96-94ec-1cb817ace42b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Range2Member_019e043c-ca40-7ca4-9286-73dec97cc2c5" xlink:href="trs-20260630.xsd#trs_Range2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_019e043c-ca40-7bcd-98a4-3ef448cc675f" xlink:to="loc_trs_Range2Member_019e043c-ca40-7ca4-9286-73dec97cc2c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Range3Member_019e043c-ca40-7000-8f6a-6840e66d330c" xlink:href="trs-20260630.xsd#trs_Range3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DamagesSoughtDomain_019e043c-ca40-7bcd-98a4-3ef448cc675f" xlink:to="loc_trs_Range3Member_019e043c-ca40-7000-8f6a-6840e66d330c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DamagesSoughtRangeDomain_019e043c-ca40-72e0-961c-d0550f2ccf7f" xlink:href="trs-20260630.xsd#trs_DamagesSoughtRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DamagesSoughtRangeAxis_019e043c-ca40-7150-9d68-34361e894c33" xlink:to="loc_trs_DamagesSoughtRangeDomain_019e043c-ca40-72e0-961c-d0550f2ccf7f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca40-790a-adc9-382f27c4b2e8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7bbd-9800-75c4cb1ada70" xlink:to="loc_srt_RangeAxis_019e043c-ca40-790a-adc9-382f27c4b2e8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-790a-adc9-382f27c4b2e8_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca40-790a-adc9-382f27c4b2e8" xlink:to="loc_srt_RangeMember_019e043c-ca40-790a-adc9-382f27c4b2e8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7b61-ab51-07da3081caa1" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca40-790a-adc9-382f27c4b2e8" xlink:to="loc_srt_RangeMember_019e043c-ca40-7b61-ab51-07da3081caa1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca40-7600-bcaf-fd4b40f6bb9e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7b61-ab51-07da3081caa1" xlink:to="loc_srt_MinimumMember_019e043c-ca40-7600-bcaf-fd4b40f6bb9e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca40-7625-b741-680e7ec6caa2" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7b61-ab51-07da3081caa1" xlink:to="loc_srt_MaximumMember_019e043c-ca40-7625-b741-680e7ec6caa2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_019e043c-ca40-7ff0-969e-875bd43f40d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7fcf-822d-b38536aa5fc7" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_019e043c-ca40-7ff0-969e-875bd43f40d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019e043c-ca40-7bb2-90e7-c2f2a4410779" xlink:href="trs-20260630.xsd#trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7fcf-822d-b38536aa5fc7" xlink:to="loc_trs_LossContingencyNumberofPlaintiffsSpecifyingDamagesSought_019e043c-ca40-7bb2-90e7-c2f2a4410779" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosLiabilityandInsuranceRecoveryAssetDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentandContingenciesAsbestosLiabilityandInsuranceRecoveryAssetDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosLiabilityandInsuranceRecoveryAssetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-76c5-bbd7-9e25f5686a70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-76c5-bbd7-9e25f5686a70" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ba-ae6b-fe245d544cbe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-76c5-bbd7-9e25f5686a70" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ba-ae6b-fe245d544cbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74ba-ae6b-fe245d544cbe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ba-ae6b-fe245d544cbe" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74ba-ae6b-fe245d544cbe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-72f3-ac42-3bbed16765b2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ba-ae6b-fe245d544cbe" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-72f3-ac42-3bbed16765b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-799d-aab0-87e7b8b37742" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-72f3-ac42-3bbed16765b2" xlink:to="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-799d-aab0-87e7b8b37742" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019e043c-ca40-7d9b-ac0d-1321a024f217" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019e043c-ca40-7d9b-ac0d-1321a024f217" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-7405-80a5-6bef49574a1b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-7405-80a5-6bef49574a1b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPaymentForClaims_019e043c-ca40-7eaf-ac68-a24f4724d99e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPaymentForClaims"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPaymentForClaims_019e043c-ca40-7eaf-ac68-a24f4724d99e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_019e043c-ca40-7733-b876-93ea13213960" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualCarryingValueCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_019e043c-ca40-7733-b876-93ea13213960" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValueNoncurrent_019e043c-ca40-765e-8da9-bc50d8a6cb46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualCarryingValueNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValueNoncurrent_019e043c-ca40-765e-8da9-bc50d8a6cb46" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_019e043c-ca40-70f2-9123-627d045158d5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingencyReceivable_019e043c-ca40-70f2-9123-627d045158d5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019e043c-ca40-701f-b4c8-461daed9e198" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingencyRelatedReceivableCarryingValuePeriodIncreaseDecrease_019e043c-ca40-701f-b4c8-461daed9e198" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivableProceeds_019e043c-ca40-7486-8f1b-39ff35453e04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyReceivableProceeds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingencyReceivableProceeds_019e043c-ca40-7486-8f1b-39ff35453e04" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet_019e043c-ca40-75bf-ba5a-81ae8e5082bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNet_019e043c-ca40-75bf-ba5a-81ae8e5082bd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019e043c-ca40-70ec-8351-f31f7a3308ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019e043c-ca40-70ec-8351-f31f7a3308ec" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaims_019e043c-ca40-7324-b02a-d4321972919f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaims"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPaymentForClaims_019e043c-ca40-7324-b02a-d4321972919f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivableCurrent_019e043c-ca40-7e30-924f-52a62a083eba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingencyReceivableCurrent_019e043c-ca40-7e30-924f-52a62a083eba" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivableNoncurrent_019e043c-ca40-7be4-aea4-46019c711791" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyReceivableNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7b7e-8852-487e974273b4" xlink:to="loc_us-gaap_LossContingencyReceivableNoncurrent_019e043c-ca40-7be4-aea4-46019c711791" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosRelatedCostsBenefitDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentandContingenciesAsbestosRelatedCostsBenefitDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentandContingenciesAsbestosRelatedCostsBenefitDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7bda-84f4-846651b77c28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-78ac-ba47-1f8f5ed4d0a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7bda-84f4-846651b77c28" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-78ac-ba47-1f8f5ed4d0a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7a5a-b7e8-8fa9fdf3c79c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-78ac-ba47-1f8f5ed4d0a6" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7a5a-b7e8-8fa9fdf3c79c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7a5a-b7e8-8fa9fdf3c79c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7a5a-b7e8-8fa9fdf3c79c" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7a5a-b7e8-8fa9fdf3c79c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7ad7-b39d-5fe1350a541b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7a5a-b7e8-8fa9fdf3c79c" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7ad7-b39d-5fe1350a541b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-79c3-a18c-01bf0934f6a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7ad7-b39d-5fe1350a541b" xlink:to="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-79c3-a18c-01bf0934f6a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-752a-bfe6-bd87e3dd6e57" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7bda-84f4-846651b77c28" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-752a-bfe6-bd87e3dd6e57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019e043c-ca40-7f82-9db7-150462faaa5e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7bda-84f4-846651b77c28" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsNetPeriodIncreaseDecrease_019e043c-ca40-7f82-9db7-150462faaa5e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesOrdinaryCourseClaimsDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesOrdinaryCourseClaimsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesOrdinaryCourseClaimsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-73ce-96bb-a0bc6390b263" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-74e7-9e37-318689c9551e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-73ce-96bb-a0bc6390b263" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-74e7-9e37-318689c9551e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019e043c-ca40-720d-9e25-29479d1f8270" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-74e7-9e37-318689c9551e" xlink:to="loc_srt_LitigationCaseAxis_019e043c-ca40-720d-9e25-29479d1f8270" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-720d-9e25-29479d1f8270_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019e043c-ca40-720d-9e25-29479d1f8270" xlink:to="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-720d-9e25-29479d1f8270_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-716e-9745-9f2ddf3ccaba" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019e043c-ca40-720d-9e25-29479d1f8270" xlink:to="loc_srt_LitigationCaseTypeDomain_019e043c-ca40-716e-9745-9f2ddf3ccaba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7b21-b9b2-6034012e387f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-74e7-9e37-318689c9551e" xlink:to="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7b21-b9b2-6034012e387f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7b21-b9b2-6034012e387f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7b21-b9b2-6034012e387f" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7b21-b9b2-6034012e387f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7f06-aabe-7bb81324292f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_019e043c-ca40-7b21-b9b2-6034012e387f" xlink:to="loc_us-gaap_LitigationStatusDomain_019e043c-ca40-7f06-aabe-7bb81324292f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ff-a933-520432ace85e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-74e7-9e37-318689c9551e" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ff-a933-520432ace85e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74ff-a933-520432ace85e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ff-a933-520432ace85e" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-74ff-a933-520432ace85e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7872-b443-d09308ea8786" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-74ff-a933-520432ace85e" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7872-b443-d09308ea8786" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_019e043c-ca40-71f3-a98c-d2df15e707cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesAwardedValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-73ce-96bb-a0bc6390b263" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_019e043c-ca40-71f3-a98c-d2df15e707cf" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesMetaldyneDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesMetaldyneDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesMetaldyneDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-74d7-a9b1-4c34b7bcab07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7ca1-8abb-b68c36b2095b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-74d7-a9b1-4c34b7bcab07" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7ca1-8abb-b68c36b2095b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-741f-a85b-5fcdb82a411c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7ca1-8abb-b68c36b2095b" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-741f-a85b-5fcdb82a411c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7ca1-8abb-b68c36b2095b" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7b8c-8eb0-693a2499ac86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7b8c-8eb0-693a2499ac86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-75eb-8113-38fa10bbe49e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-75eb-8113-38fa10bbe49e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_019e043c-ca40-7e96-8a8f-a772d4f88a91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-74d7-a9b1-4c34b7bcab07" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_019e043c-ca40-7e96-8a8f-a772d4f88a91" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesMetaldyneDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesMetaldyneDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesMetaldyneDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-74d7-a9b1-4c34b7bcab07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7ca1-8abb-b68c36b2095b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-74d7-a9b1-4c34b7bcab07" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7ca1-8abb-b68c36b2095b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7ca1-8abb-b68c36b2095b" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7b8c-8eb0-693a2499ac86_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7b8c-8eb0-693a2499ac86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-75eb-8113-38fa10bbe49e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7b8c-8eb0-693a2499ac86" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-75eb-8113-38fa10bbe49e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_019e043c-ca40-7e96-8a8f-a772d4f88a91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-74d7-a9b1-4c34b7bcab07" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_019e043c-ca40-7e96-8a8f-a772d4f88a91" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/CommitmentsandContingenciesEnvironmentalDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#CommitmentsandContingenciesEnvironmentalDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/CommitmentsandContingenciesEnvironmentalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7ad0-a8b5-60643bebd3fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7028-b9c8-223250b054a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7ad0-a8b5-60643bebd3fa" xlink:to="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7028-b9c8-223250b054a9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7fe0-b788-8c5643fff3a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019e043c-ca40-7028-b9c8-223250b054a9" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7fe0-b788-8c5643fff3a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7fe0-b788-8c5643fff3a8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7fe0-b788-8c5643fff3a8" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7fe0-b788-8c5643fff3a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-78f7-8fc7-871977550370" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7fe0-b788-8c5643fff3a8" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-78f7-8fc7-871977550370" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-7b18-a43d-c6c611cedb02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnvironmentalIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-78f7-8fc7-871977550370" xlink:to="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-7b18-a43d-c6c611cedb02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-7ef1-a0c0-9c0d407a2cef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7ad0-a8b5-60643bebd3fa" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-7ef1-a0c0-9c0d407a2cef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019e043c-ca40-7977-bf0e-2312ae7fc9e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019e043c-ca40-7ad0-a8b5-60643bebd3fa" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross_019e043c-ca40-7977-bf0e-2312ae7fc9e7" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SegmentInformationNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#SegmentInformationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SegmentInformationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7ca3-aa5c-953449142475" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7ca3-aa5c-953449142475" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019e043c-ca40-7ad4-ac09-212e76d996e7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:to="loc_srt_ConsolidationItemsAxis_019e043c-ca40-7ad4-ac09-212e76d996e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e043c-ca40-7ad4-ac09-212e76d996e7_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019e043c-ca40-7ad4-ac09-212e76d996e7" xlink:to="loc_srt_ConsolidationItemsDomain_019e043c-ca40-7ad4-ac09-212e76d996e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019e043c-ca40-7b9a-8b9c-c8a4ae159301" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019e043c-ca40-7ad4-ac09-212e76d996e7" xlink:to="loc_srt_ConsolidationItemsDomain_019e043c-ca40-7b9a-8b9c-c8a4ae159301" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7959-adec-9241d7f5dfbe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7959-adec-9241d7f5dfbe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca40-7959-adec-9241d7f5dfbe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7959-adec-9241d7f5dfbe" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca40-7959-adec-9241d7f5dfbe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca40-7445-b23a-b2fd9a5b7631" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7959-adec-9241d7f5dfbe" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca40-7445-b23a-b2fd9a5b7631" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PackagingReportableSegmentMember_019e043c-ca40-7d66-bc88-71a6bd2bdba5" xlink:href="trs-20260630.xsd#trs_PackagingReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca40-7445-b23a-b2fd9a5b7631" xlink:to="loc_trs_PackagingReportableSegmentMember_019e043c-ca40-7d66-bc88-71a6bd2bdba5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsAxis_019e043c-ca40-7568-a116-4a6dc5b44d2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:to="loc_us-gaap_SubsegmentsAxis_019e043c-ca40-7568-a116-4a6dc5b44d2d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsDomain_019e043c-ca40-7568-a116-4a6dc5b44d2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsegmentsAxis_019e043c-ca40-7568-a116-4a6dc5b44d2d" xlink:to="loc_us-gaap_SubsegmentsDomain_019e043c-ca40-7568-a116-4a6dc5b44d2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsDomain_019e043c-ca40-71fd-9108-70d15e8d988a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsegmentsAxis_019e043c-ca40-7568-a116-4a6dc5b44d2d" xlink:to="loc_us-gaap_SubsegmentsDomain_019e043c-ca40-71fd-9108-70d15e8d988a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019e043c-ca40-73e8-b7c4-13836bec4655" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:to="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019e043c-ca40-73e8-b7c4-13836bec4655" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019e043c-ca40-73e8-b7c4-13836bec4655_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019e043c-ca40-73e8-b7c4-13836bec4655" xlink:to="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019e043c-ca40-73e8-b7c4-13836bec4655_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019e043c-ca40-774f-b14b-9769ebcb4e93" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsegmentsConsolidationItemsAxis_019e043c-ca40-73e8-b7c4-13836bec4655" xlink:to="loc_us-gaap_SubsegmentsConsolidationItemsDomain_019e043c-ca40-774f-b14b-9769ebcb4e93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019e043c-ca40-747d-9250-2ae16fbcf4f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:to="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019e043c-ca40-747d-9250-2ae16fbcf4f8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019e043c-ca40-747d-9250-2ae16fbcf4f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019e043c-ca40-747d-9250-2ae16fbcf4f8" xlink:to="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019e043c-ca40-747d-9250-2ae16fbcf4f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019e043c-ca40-74a9-b3f2-d679c593a548" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisAxis_019e043c-ca40-747d-9250-2ae16fbcf4f8" xlink:to="loc_us-gaap_SegmentReportingReportedAsIfOldSegmentationBasisDomain_019e043c-ca40-74a9-b3f2-d679c593a548" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementAxis_019e043c-ca40-762c-9c01-a5d3437d426d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RestatementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7b16-ae81-fca5e632aebd" xlink:to="loc_srt_RestatementAxis_019e043c-ca40-762c-9c01-a5d3437d426d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019e043c-ca40-762c-9c01-a5d3437d426d_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_019e043c-ca40-762c-9c01-a5d3437d426d" xlink:to="loc_srt_RestatementDomain_019e043c-ca40-762c-9c01-a5d3437d426d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RestatementDomain_019e043c-ca40-7aed-9447-8cef15e98d63" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RestatementDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_019e043c-ca40-762c-9c01-a5d3437d426d" xlink:to="loc_srt_RestatementDomain_019e043c-ca40-7aed-9447-8cef15e98d63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingCodmProfitLossMeasureHowUsedDescription_019e043c-ca40-77f6-8aaf-28ad448672df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingCodmProfitLossMeasureHowUsedDescription"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7ca3-aa5c-953449142475" xlink:to="loc_us-gaap_SegmentReportingCodmProfitLossMeasureHowUsedDescription_019e043c-ca40-77f6-8aaf-28ad448672df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingCodmIndividualTitleAndPositionOrGroupOrCommitteeNameExtensibleEnumeration_019e043c-ca40-7f83-9014-6d5e09b7d183" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingCodmIndividualTitleAndPositionOrGroupOrCommitteeNameExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7ca3-aa5c-953449142475" xlink:to="loc_us-gaap_SegmentReportingCodmIndividualTitleAndPositionOrGroupOrCommitteeNameExtensibleEnumeration_019e043c-ca40-7f83-9014-6d5e09b7d183" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019e043c-ca40-7b58-97fe-096f17dc378a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7ca3-aa5c-953449142475" xlink:to="loc_us-gaap_NumberOfReportableSegments_019e043c-ca40-7b58-97fe-096f17dc378a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CorporateExpensesAllocatedToSegment_019e043c-ca40-7eac-b2f2-f50876a9b05f" xlink:href="trs-20260630.xsd#trs_CorporateExpensesAllocatedToSegment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7ca3-aa5c-953449142475" xlink:to="loc_trs_CorporateExpensesAllocatedToSegment_019e043c-ca40-7eac-b2f2-f50876a9b05f" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SegmentReportingSegmentActivityDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#SegmentReportingSegmentActivityDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SegmentReportingSegmentActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7248-ac94-0f3d4f02037d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7248-ac94-0f3d4f02037d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7894-ae64-34ef99627262" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7248-ac94-0f3d4f02037d" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7894-ae64-34ef99627262" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca40-7894-ae64-34ef99627262_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7894-ae64-34ef99627262" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca40-7894-ae64-34ef99627262_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019e043c-ca40-7259-80a9-0cb45ed856ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019e043c-ca40-7894-ae64-34ef99627262" xlink:to="loc_us-gaap_SegmentDomain_019e043c-ca40-7259-80a9-0cb45ed856ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_PackagingReportableSegmentMember_019e043c-ca40-70c6-a2f5-bf0b287b2230" xlink:href="trs-20260630.xsd#trs_PackagingReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca40-7259-80a9-0cb45ed856ed" xlink:to="loc_trs_PackagingReportableSegmentMember_019e043c-ca40-70c6-a2f5-bf0b287b2230" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AerospaceReportableSegmentMember_019e043c-ca40-7b9a-84b6-33166dbc8a8f" xlink:href="trs-20260630.xsd#trs_AerospaceReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca40-7259-80a9-0cb45ed856ed" xlink:to="loc_trs_AerospaceReportableSegmentMember_019e043c-ca40-7b9a-84b6-33166dbc8a8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateMember_019e043c-ca40-790d-8bd3-655062717c87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca40-7259-80a9-0cb45ed856ed" xlink:to="loc_us-gaap_CorporateMember_019e043c-ca40-790d-8bd3-655062717c87" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SpecialtyProductsReportableSegmentMember_019e043c-ca40-7a57-b42e-863de31dfb9a" xlink:href="trs-20260630.xsd#trs_SpecialtyProductsReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca40-7259-80a9-0cb45ed856ed" xlink:to="loc_trs_SpecialtyProductsReportableSegmentMember_019e043c-ca40-7a57-b42e-863de31dfb9a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember_019e043c-ca40-75a4-8ef3-2df348b1f672" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019e043c-ca40-7259-80a9-0cb45ed856ed" xlink:to="loc_us-gaap_ReportableSegmentAggregationBeforeOtherOperatingSegmentMember_019e043c-ca40-75a4-8ef3-2df348b1f672" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-78fd-a6e4-acdc390168e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7248-ac94-0f3d4f02037d" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-78fd-a6e4-acdc390168e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-78fd-a6e4-acdc390168e1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-78fd-a6e4-acdc390168e1" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-78fd-a6e4-acdc390168e1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-79fd-acd2-79f68fd278de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-78fd-a6e4-acdc390168e1" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-79fd-acd2-79f68fd278de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ArrowEngineMember_019e043c-ca40-729b-b0f0-3a3b03728b97" xlink:href="trs-20260630.xsd#trs_ArrowEngineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-79fd-acd2-79f68fd278de" xlink:to="loc_trs_ArrowEngineMember_019e043c-ca40-729b-b0f0-3a3b03728b97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7535-b199-7871ed5fd8cb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7248-ac94-0f3d4f02037d" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7535-b199-7871ed5fd8cb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7535-b199-7871ed5fd8cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7535-b199-7871ed5fd8cb" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-7535-b199-7871ed5fd8cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-785a-b6de-7cbaa8b3b481" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_019e043c-ca40-7535-b199-7871ed5fd8cb" xlink:to="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-785a-b6de-7cbaa8b3b481" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-77d3-86ec-e07c7dc9a27e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EnvironmentalIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-785a-b6de-7cbaa8b3b481" xlink:to="loc_us-gaap_EnvironmentalIssueMember_019e043c-ca40-77d3-86ec-e07c7dc9a27e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-7c76-b7b7-10d0da9caeb9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AsbestosIssueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_019e043c-ca40-785a-b6de-7cbaa8b3b481" xlink:to="loc_us-gaap_AsbestosIssueMember_019e043c-ca40-7c76-b7b7-10d0da9caeb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7a1f-be9f-cfc27b5d07a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019e043c-ca40-7248-ac94-0f3d4f02037d" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7a1f-be9f-cfc27b5d07a9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7a1f-be9f-cfc27b5d07a9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7a1f-be9f-cfc27b5d07a9" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7a1f-be9f-cfc27b5d07a9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7755-9079-74c059e6d4e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7a1f-be9f-cfc27b5d07a9" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7755-9079-74c059e6d4e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca40-7d1c-9095-1c43a1fc9a90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7755-9079-74c059e6d4e9" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019e043c-ca40-7d1c-9095-1c43a1fc9a90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019e043c-ca40-7fb2-aa19-5e5b3813e8eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_Revenues_019e043c-ca40-7fb2-aa19-5e5b3813e8eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019e043c-ca40-730d-b3c0-af71b171e1c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019e043c-ca40-730d-b3c0-af71b171e1c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e043c-ca40-746c-b0e5-645ea50bae37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e043c-ca40-746c-b0e5-645ea50bae37" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019e043c-ca40-72a3-927a-c38e87b35364" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019e043c-ca40-72a3-927a-c38e87b35364" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SegmentOperatingProfit_019e043c-ca40-7f38-a256-c8dab70e91b9" xlink:href="trs-20260630.xsd#trs_SegmentOperatingProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_trs_SegmentOperatingProfit_019e043c-ca40-7f38-a256-c8dab70e91b9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019e043c-ca40-765f-a5de-4a164530bf56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_OperatingIncomeLoss_019e043c-ca40-765f-a5de-4a164530bf56" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e043c-ca40-777a-87c9-894dd1bf4fcd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e043c-ca40-777a-87c9-894dd1bf4fcd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019e043c-ca40-7780-adab-19bb7f24a3a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019e043c-ca40-7780-adab-19bb7f24a3a6" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e043c-ca40-7d61-8e1c-42163d677f78" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e043c-ca40-7d61-8e1c-42163d677f78" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_RealignmentSeveranceAndConsultingCosts_019e043c-ca40-7673-abba-0bcf849cd565" xlink:href="trs-20260630.xsd#trs_RealignmentSeveranceAndConsultingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_trs_RealignmentSeveranceAndConsultingCosts_019e043c-ca40-7673-abba-0bcf849cd565" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SystemImplementationCosts_019e043c-ca40-70de-947c-5768a32071aa" xlink:href="trs-20260630.xsd#trs_SystemImplementationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_trs_SystemImplementationCosts_019e043c-ca40-70de-947c-5768a32071aa" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019e043c-ca40-7d81-85b4-fd6cb4cc6e2a" xlink:href="trs-20260630.xsd#trs_MergersAcquisitionsDiligenceAndTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_trs_MergersAcquisitionsDiligenceAndTransactionCosts_019e043c-ca40-7d81-85b4-fd6cb4cc6e2a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-ca40-73f4-a5ee-69f390ef2def" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_019e043c-ca40-73f4-a5ee-69f390ef2def" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-771a-8a8d-21dac8e8fef7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGrossPeriodIncreaseDecrease_019e043c-ca40-771a-8a8d-21dac8e8fef7" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_019e043c-ca40-7f76-8e24-34422b3887ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_019e043c-ca40-7f76-8e24-34422b3887ea" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019e043c-ca40-7a29-a722-52d7a1ee9e52" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentExpenditureAdditionToLongLivedAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_SegmentExpenditureAdditionToLongLivedAssets_019e043c-ca40-7a29-a722-52d7a1ee9e52" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019e043c-ca40-78a6-a01a-72bd45d0b444" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019e043c-ca40-78a6-a01a-72bd45d0b444" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e043c-ca40-7e34-be04-bef7f8a12440" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_Assets_019e043c-ca40-7e34-be04-bef7f8a12440" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e043c-ca40-74fb-b6eb-8e2d1f347aa9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e043c-ca40-74fb-b6eb-8e2d1f347aa9" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyReceivable_019e043c-ca40-7ff2-b6c5-4e55fcac91fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_LossContingencyReceivable_019e043c-ca40-7ff2-b6c5-4e55fcac91fd" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_OutsideBasisDifferenceOnHeldForSaleAssets_019e043c-ca40-76c1-955c-ea1c32ed537c" xlink:href="trs-20260630.xsd#trs_OutsideBasisDifferenceOnHeldForSaleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_trs_OutsideBasisDifferenceOnHeldForSaleAssets_019e043c-ca40-76c1-955c-ea1c32ed537c" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestAndOtherIncome_019fa473-4518-7156-8090-cc67f94cccd7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestAndOtherIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019e043c-ca40-7b54-8dc7-e378f30fb479" xlink:to="loc_us-gaap_InterestAndOtherIncome_019fa473-4518-7156-8090-cc67f94cccd7" xlink:type="arc" order="21"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsStockOptionActivityTableDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#EquityAwardsStockOptionActivityTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsStockOptionActivityTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aae-a15e-8bc7b2000064" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-7107-9080-cc60d09b5f3e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aae-a15e-8bc7b2000064" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-7107-9080-cc60d09b5f3e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7f83-bced-0a8955a4e1ce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-7107-9080-cc60d09b5f3e" xlink:to="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7f83-bced-0a8955a4e1ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7f83-bced-0a8955a4e1ce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7f83-bced-0a8955a4e1ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7f83-bced-0a8955a4e1ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7b53-96cb-7d128e4fe477" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7f83-bced-0a8955a4e1ce" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7b53-96cb-7d128e4fe477" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-792f-884f-07b1372c6ded" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7b53-96cb-7d128e4fe477" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-792f-884f-07b1372c6ded" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019e043c-ca40-7ae9-a49f-2e34eae9f44c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aae-a15e-8bc7b2000064" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019e043c-ca40-7ae9-a49f-2e34eae9f44c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019e043c-ca40-7200-a5ab-1dda49c983c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aae-a15e-8bc7b2000064" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019e043c-ca40-7200-a5ab-1dda49c983c1" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#EquityAwardsStockOptionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-79ed-b8f5-710321dae183" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-79ed-b8f5-710321dae183" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-7b51-b992-2acc619920c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-79ed-b8f5-710321dae183" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-7b51-b992-2acc619920c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-79ed-b8f5-710321dae183" xlink:to="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7236-b572-2edf70e9296d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7236-b572-2edf70e9296d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7562-91f9-384a0c0eff87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7562-91f9-384a0c0eff87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-7bc3-a47e-38fa50a44652" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7562-91f9-384a0c0eff87" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-7bc3-a47e-38fa50a44652" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019e043c-ca40-755d-8106-a5bfc2dec7ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019e043c-ca40-755d-8106-a5bfc2dec7ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-78c6-bc7f-5f5166bfe207" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-78c6-bc7f-5f5166bfe207" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019e043c-ca40-7949-9645-fb8f338b0d0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019e043c-ca40-7949-9645-fb8f338b0d0d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_StockOptionsVested_019e043c-ca40-717a-9f87-cb46d5db51bc" xlink:href="trs-20260630.xsd#trs_StockOptionsVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_trs_StockOptionsVested_019e043c-ca40-717a-9f87-cb46d5db51bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019e043c-ca40-748c-9d68-5570cf39f2d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019e043c-ca40-748c-9d68-5570cf39f2d9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-72d4-9f33-8a308e499b43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-72d4-9f33-8a308e499b43" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-7462-80e5-c76eba6e56c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-7462-80e5-c76eba6e56c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-732f-8837-2b117dc6c582" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-732f-8837-2b117dc6c582" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e043c-ca40-74db-935b-c4bc06f854a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e043c-ca40-74db-935b-c4bc06f854a6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e043c-ca40-7121-8be3-bb7949555f0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e043c-ca40-7121-8be3-bb7949555f0b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_019e043c-ca40-7972-92b6-c1650b3bdb30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_019e043c-ca40-7972-92b6-c1650b3bdb30" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-70e2-b72c-35d4e8d77aef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-70e2-b72c-35d4e8d77aef" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#EquityAwardsStockOptionsNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsStockOptionsNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-79ed-b8f5-710321dae183" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-79ed-b8f5-710321dae183" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-79ed-b8f5-710321dae183" xlink:to="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7236-b572-2edf70e9296d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7236-b572-2edf70e9296d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7562-91f9-384a0c0eff87" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7236-b572-2edf70e9296d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7562-91f9-384a0c0eff87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-7bc3-a47e-38fa50a44652" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7562-91f9-384a0c0eff87" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-7bc3-a47e-38fa50a44652" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019e043c-ca40-755d-8106-a5bfc2dec7ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019e043c-ca40-755d-8106-a5bfc2dec7ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-78c6-bc7f-5f5166bfe207" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-78c6-bc7f-5f5166bfe207" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019e043c-ca40-7949-9645-fb8f338b0d0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber_019e043c-ca40-7949-9645-fb8f338b0d0d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_StockOptionsVested_019e043c-ca40-717a-9f87-cb46d5db51bc" xlink:href="trs-20260630.xsd#trs_StockOptionsVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_trs_StockOptionsVested_019e043c-ca40-717a-9f87-cb46d5db51bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019e043c-ca40-748c-9d68-5570cf39f2d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019e043c-ca40-748c-9d68-5570cf39f2d9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-72d4-9f33-8a308e499b43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-72d4-9f33-8a308e499b43" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-7462-80e5-c76eba6e56c0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-7462-80e5-c76eba6e56c0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-732f-8837-2b117dc6c582" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-732f-8837-2b117dc6c582" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e043c-ca40-74db-935b-c4bc06f854a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019e043c-ca40-74db-935b-c4bc06f854a6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e043c-ca40-7121-8be3-bb7949555f0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019e043c-ca40-7121-8be3-bb7949555f0b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_019e043c-ca40-7972-92b6-c1650b3bdb30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments_019e043c-ca40-7972-92b6-c1650b3bdb30" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-70e2-b72c-35d4e8d77aef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7f69-90d3-87acdaf3bb0e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-70e2-b72c-35d4e8d77aef" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#EquityAwardsRestrictedStockUnitsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-709b-a927-aa44961b495e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019e043c-ca40-709b-a927-aa44961b495e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-7528-bd81-91fac4835806_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-7528-bd81-91fac4835806_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-751a-aecd-f6e49d0cc700" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-751a-aecd-f6e49d0cc700" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019e043c-ca40-7fe3-94a5-2efb26a8fc8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationShareBasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-751a-aecd-f6e49d0cc700" xlink:to="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019e043c-ca40-7fe3-94a5-2efb26a8fc8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:href="trs-20260630.xsd#trs_MetricTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeDomain_019e043c-ca40-701c-8969-2c4ab5501ae4_default" xlink:href="trs-20260630.xsd#trs_MetricTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:to="loc_trs_MetricTypeDomain_019e043c-ca40-701c-8969-2c4ab5501ae4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:href="trs-20260630.xsd#trs_MetricTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:to="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A3YearEpsCagrMetricMember_019e043c-ca40-75f2-924b-0c5533acb631" xlink:href="trs-20260630.xsd#trs_A3YearEpsCagrMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_A3YearEpsCagrMetricMember_019e043c-ca40-75f2-924b-0c5533acb631" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_TotalshareholderreturnmetricMember_019e043c-ca40-7c93-933d-5547c13f20f0" xlink:href="trs-20260630.xsd#trs_TotalshareholderreturnmetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_TotalshareholderreturnmetricMember_019e043c-ca40-7c93-933d-5547c13f20f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AveragestockpriceMember_019e043c-ca40-751d-94f3-403854ced71f" xlink:href="trs-20260630.xsd#trs_AveragestockpriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_AveragestockpriceMember_019e043c-ca40-751d-94f3-403854ced71f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CashReturnOnNetAssetsMetricMember_019e043c-ca40-7c38-a8fb-b731fb8adf9a" xlink:href="trs-20260630.xsd#trs_CashReturnOnNetAssetsMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_CashReturnOnNetAssetsMetricMember_019e043c-ca40-7c38-a8fb-b731fb8adf9a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember_019e043c-ca40-79af-b339-de41ce6e1397" xlink:href="trs-20260630.xsd#trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember_019e043c-ca40-79af-b339-de41ce6e1397" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7886-8ffb-5ef6be8f9c1d_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:to="loc_srt_RangeMember_019e043c-ca40-7886-8ffb-5ef6be8f9c1d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:to="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca40-7571-aef9-2b442b52bdbc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:to="loc_srt_MinimumMember_019e043c-ca40-7571-aef9-2b442b52bdbc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca40-715e-9b5d-501ad2caa0ec" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:to="loc_srt_MaximumMember_019e043c-ca40-715e-9b5d-501ad2caa0ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e043c-ca40-7dde-b11d-8890494343fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:to="loc_us-gaap_PlanNameDomain_019e043c-ca40-7dde-b11d-8890494343fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:to="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan1Member_019e043c-ca40-7998-a4a5-6e1ea0ef9c61" xlink:href="trs-20260630.xsd#trs_Plan1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan1Member_019e043c-ca40-7998-a4a5-6e1ea0ef9c61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan2Member_019e043c-ca40-7c9c-8f65-313aa37e1510" xlink:href="trs-20260630.xsd#trs_Plan2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan2Member_019e043c-ca40-7c9c-8f65-313aa37e1510" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan3Member_019e043c-ca40-738d-b41d-f063a1743c65" xlink:href="trs-20260630.xsd#trs_Plan3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan3Member_019e043c-ca40-738d-b41d-f063a1743c65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan4Member_019e043c-ca40-714a-8f4c-c0c21d4fa236" xlink:href="trs-20260630.xsd#trs_Plan4Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan4Member_019e043c-ca40-714a-8f4c-c0c21d4fa236" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan5Member_019e043c-ca40-7a4d-9d19-16a8f7eefb5c" xlink:href="trs-20260630.xsd#trs_Plan5Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan5Member_019e043c-ca40-7a4d-9d19-16a8f7eefb5c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan7Member_019e043c-ca40-7d45-ba54-45c747874ff9" xlink:href="trs-20260630.xsd#trs_Plan7Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan7Member_019e043c-ca40-7d45-ba54-45c747874ff9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan8Member_019e043c-ca40-780e-a1a8-4fc9a5e6e854" xlink:href="trs-20260630.xsd#trs_Plan8Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan8Member_019e043c-ca40-780e-a1a8-4fc9a5e6e854" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7286-b2fc-8047421470dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7286-b2fc-8047421470dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-7c63-9a69-650468b1a2c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-7c63-9a69-650468b1a2c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-79ce-9680-d36d3ffff3e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-79ce-9680-d36d3ffff3e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-78d0-9efd-db4e5a35f257_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-78d0-9efd-db4e5a35f257_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-7701-8958-054afab23ade" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-7701-8958-054afab23ade" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_019e043c-ca40-72cd-b8aa-0659a8e5cb05" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-7701-8958-054afab23ade" xlink:to="loc_srt_DirectorMember_019e043c-ca40-72cd-b8aa-0659a8e5cb05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019e043c-ca40-7c2c-bc80-1eadd80ece60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:to="loc_us-gaap_DividendsDomain_019e043c-ca40-7c2c-bc80-1eadd80ece60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019e043c-ca40-791a-912c-d8270857d7de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:to="loc_us-gaap_DividendsDomain_019e043c-ca40-791a-912c-d8270857d7de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:href="trs-20260630.xsd#trs_DividendEquivalentAxisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-73bd-aede-0b001708ef90_default" xlink:href="trs-20260630.xsd#trs_DividendEquivalentAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:to="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-73bd-aede-0b001708ef90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-7359-9553-8cbd1dc8ec33" xlink:href="trs-20260630.xsd#trs_DividendEquivalentAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:to="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-7359-9553-8cbd1dc8ec33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentMember_019e043c-ca40-74ad-97ff-fe1a7518982d" xlink:href="trs-20260630.xsd#trs_DividendEquivalentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-7359-9553-8cbd1dc8ec33" xlink:to="loc_trs_DividendEquivalentMember_019e043c-ca40-74ad-97ff-fe1a7518982d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_019e043c-ca40-761e-ae50-a377e61e199a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_019e043c-ca40-761e-ae50-a377e61e199a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e043c-ca40-7d47-9b7e-0672f0ff13e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e043c-ca40-7d47-9b7e-0672f0ff13e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019e043c-ca40-763a-8b4b-23bb5cc19f43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019e043c-ca40-763a-8b4b-23bb5cc19f43" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_019e043c-ca40-7390-ab54-f3f01f901161" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_019e043c-ca40-7390-ab54-f3f01f901161" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_019e043c-ca40-7dec-ae93-ad9c60e4a3a9" xlink:href="trs-20260630.xsd#trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_019e043c-ca40-7dec-ae93-ad9c60e4a3a9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-71c1-b09c-d78602d9a3a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-71c1-b09c-d78602d9a3a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-7f2a-9e1e-fd22e9ca2c05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-7f2a-9e1e-fd22e9ca2c05" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_019e043c-ca40-70cb-af27-c791f86d9900" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_019e043c-ca40-70cb-af27-c791f86d9900" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_019e043c-ca40-7c01-8421-5775baa341b6" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_019e043c-ca40-7c01-8421-5775baa341b6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_019e043c-ca40-7c98-81a1-3726b309f082" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_019e043c-ca40-7c98-81a1-3726b309f082" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-7b26-a7b2-1f9bb4b1c67b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-7b26-a7b2-1f9bb4b1c67b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-79eb-905c-a1ecf809e5da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-79eb-905c-a1ecf809e5da" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-7dea-82e5-bd521faba28d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-7dea-82e5-bd521faba28d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e043c-ca40-7e94-b545-afae05c5b343" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e043c-ca40-7e94-b545-afae05c5b343" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails_1" xlink:type="simple" xlink:href="trs-20260630.xsd#EquityAwardsRestrictedStockUnitsNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-7528-bd81-91fac4835806_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-7528-bd81-91fac4835806_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-751a-aecd-f6e49d0cc700" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis_019e043c-ca40-7528-bd81-91fac4835806" xlink:to="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-751a-aecd-f6e49d0cc700" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019e043c-ca40-7fe3-94a5-2efb26a8fc8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationShareBasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityBasedArrangementsIndividualContractsTypeOfDeferredCompensationDomain_019e043c-ca40-751a-aecd-f6e49d0cc700" xlink:to="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019e043c-ca40-7fe3-94a5-2efb26a8fc8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:href="trs-20260630.xsd#trs_MetricTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeDomain_019e043c-ca40-701c-8969-2c4ab5501ae4_default" xlink:href="trs-20260630.xsd#trs_MetricTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:to="loc_trs_MetricTypeDomain_019e043c-ca40-701c-8969-2c4ab5501ae4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:href="trs-20260630.xsd#trs_MetricTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_MetricTypeAxis_019e043c-ca40-701c-8969-2c4ab5501ae4" xlink:to="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A3YearEpsCagrMetricMember_019e043c-ca40-75f2-924b-0c5533acb631" xlink:href="trs-20260630.xsd#trs_A3YearEpsCagrMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_A3YearEpsCagrMetricMember_019e043c-ca40-75f2-924b-0c5533acb631" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_TotalshareholderreturnmetricMember_019e043c-ca40-7c93-933d-5547c13f20f0" xlink:href="trs-20260630.xsd#trs_TotalshareholderreturnmetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_TotalshareholderreturnmetricMember_019e043c-ca40-7c93-933d-5547c13f20f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AveragestockpriceMember_019e043c-ca40-751d-94f3-403854ced71f" xlink:href="trs-20260630.xsd#trs_AveragestockpriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_AveragestockpriceMember_019e043c-ca40-751d-94f3-403854ced71f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CashReturnOnNetAssetsMetricMember_019e043c-ca40-7c38-a8fb-b731fb8adf9a" xlink:href="trs-20260630.xsd#trs_CashReturnOnNetAssetsMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_CashReturnOnNetAssetsMetricMember_019e043c-ca40-7c38-a8fb-b731fb8adf9a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember_019e043c-ca40-79af-b339-de41ce6e1397" xlink:href="trs-20260630.xsd#trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_MetricTypeDomain_019e043c-ca40-7144-9467-d0d2379690f5" xlink:to="loc_trs_EarningsPerShareCompoundAnnualGrowthRateMetricMember_019e043c-ca40-79af-b339-de41ce6e1397" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7886-8ffb-5ef6be8f9c1d_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:to="loc_srt_RangeMember_019e043c-ca40-7886-8ffb-5ef6be8f9c1d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e043c-ca40-7886-8ffb-5ef6be8f9c1d" xlink:to="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e043c-ca40-7571-aef9-2b442b52bdbc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:to="loc_srt_MinimumMember_019e043c-ca40-7571-aef9-2b442b52bdbc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e043c-ca40-715e-9b5d-501ad2caa0ec" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e043c-ca40-7a45-a276-0b6087da342a" xlink:to="loc_srt_MaximumMember_019e043c-ca40-715e-9b5d-501ad2caa0ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e043c-ca40-7dde-b11d-8890494343fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:to="loc_us-gaap_PlanNameDomain_019e043c-ca40-7dde-b11d-8890494343fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019e043c-ca40-7dde-b11d-8890494343fa" xlink:to="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan1Member_019e043c-ca40-7998-a4a5-6e1ea0ef9c61" xlink:href="trs-20260630.xsd#trs_Plan1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan1Member_019e043c-ca40-7998-a4a5-6e1ea0ef9c61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan2Member_019e043c-ca40-7c9c-8f65-313aa37e1510" xlink:href="trs-20260630.xsd#trs_Plan2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan2Member_019e043c-ca40-7c9c-8f65-313aa37e1510" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan3Member_019e043c-ca40-738d-b41d-f063a1743c65" xlink:href="trs-20260630.xsd#trs_Plan3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan3Member_019e043c-ca40-738d-b41d-f063a1743c65" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan4Member_019e043c-ca40-714a-8f4c-c0c21d4fa236" xlink:href="trs-20260630.xsd#trs_Plan4Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan4Member_019e043c-ca40-714a-8f4c-c0c21d4fa236" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan5Member_019e043c-ca40-7a4d-9d19-16a8f7eefb5c" xlink:href="trs-20260630.xsd#trs_Plan5Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan5Member_019e043c-ca40-7a4d-9d19-16a8f7eefb5c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan7Member_019e043c-ca40-7d45-ba54-45c747874ff9" xlink:href="trs-20260630.xsd#trs_Plan7Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan7Member_019e043c-ca40-7d45-ba54-45c747874ff9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Plan8Member_019e043c-ca40-780e-a1a8-4fc9a5e6e854" xlink:href="trs-20260630.xsd#trs_Plan8Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019e043c-ca40-7552-add3-d28d13e5043f" xlink:to="loc_trs_Plan8Member_019e043c-ca40-780e-a1a8-4fc9a5e6e854" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7286-b2fc-8047421470dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7286-b2fc-8047421470dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7286-b2fc-8047421470dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-7c63-9a69-650468b1a2c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-7c63-9a69-650468b1a2c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-79ce-9680-d36d3ffff3e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7a53-8a20-bd49ec2d6eaa" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-79ce-9680-d36d3ffff3e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-78d0-9efd-db4e5a35f257_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-78d0-9efd-db4e5a35f257_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-7701-8958-054afab23ade" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_019e043c-ca40-78d0-9efd-db4e5a35f257" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-7701-8958-054afab23ade" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_019e043c-ca40-72cd-b8aa-0659a8e5cb05" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019e043c-ca40-7701-8958-054afab23ade" xlink:to="loc_srt_DirectorMember_019e043c-ca40-72cd-b8aa-0659a8e5cb05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019e043c-ca40-7c2c-bc80-1eadd80ece60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:to="loc_us-gaap_DividendsDomain_019e043c-ca40-7c2c-bc80-1eadd80ece60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019e043c-ca40-791a-912c-d8270857d7de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_019e043c-ca40-7c2c-bc80-1eadd80ece60" xlink:to="loc_us-gaap_DividendsDomain_019e043c-ca40-791a-912c-d8270857d7de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:href="trs-20260630.xsd#trs_DividendEquivalentAxisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-714e-a939-1cc381ffa874" xlink:to="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-73bd-aede-0b001708ef90_default" xlink:href="trs-20260630.xsd#trs_DividendEquivalentAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:to="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-73bd-aede-0b001708ef90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-7359-9553-8cbd1dc8ec33" xlink:href="trs-20260630.xsd#trs_DividendEquivalentAxisDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_trs_DividendEquivalentAxisAxis_019e043c-ca40-73bd-aede-0b001708ef90" xlink:to="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-7359-9553-8cbd1dc8ec33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DividendEquivalentMember_019e043c-ca40-74ad-97ff-fe1a7518982d" xlink:href="trs-20260630.xsd#trs_DividendEquivalentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_trs_DividendEquivalentAxisDomain_019e043c-ca40-7359-9553-8cbd1dc8ec33" xlink:to="loc_trs_DividendEquivalentMember_019e043c-ca40-74ad-97ff-fe1a7518982d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_019e043c-ca40-761e-ae50-a377e61e199a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued_019e043c-ca40-761e-ae50-a377e61e199a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e043c-ca40-7d47-9b7e-0672f0ff13e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e043c-ca40-7d47-9b7e-0672f0ff13e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019e043c-ca40-763a-8b4b-23bb5cc19f43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019e043c-ca40-763a-8b4b-23bb5cc19f43" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_019e043c-ca40-7390-ab54-f3f01f901161" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageEarnedBasedOnMetricOverPerformancePeriod_019e043c-ca40-7390-ab54-f3f01f901161" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_019e043c-ca40-7dec-ae93-ad9c60e4a3a9" xlink:href="trs-20260630.xsd#trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardPerformancePeriodComplete_019e043c-ca40-7dec-ae93-ad9c60e4a3a9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-71c1-b09c-d78602d9a3a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019e043c-ca40-71c1-b09c-d78602d9a3a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-7f2a-9e1e-fd22e9ca2c05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019e043c-ca40-7f2a-9e1e-fd22e9ca2c05" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_019e043c-ca40-70cb-af27-c791f86d9900" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfPerformanceMetricsInRestrictedSharesAwardTypePlan_019e043c-ca40-70cb-af27-c791f86d9900" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_019e043c-ca40-7c01-8421-5775baa341b6" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAmountOfSharesEarnedOfTargetAward_019e043c-ca40-7c01-8421-5775baa341b6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_019e043c-ca40-7c98-81a1-3726b309f082" xlink:href="trs-20260630.xsd#trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_trs_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardPercentageAttained_019e043c-ca40-7c98-81a1-3726b309f082" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-7b26-a7b2-1f9bb4b1c67b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019e043c-ca40-7b26-a7b2-1f9bb4b1c67b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-79eb-905c-a1ecf809e5da" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019e043c-ca40-79eb-905c-a1ecf809e5da" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-7dea-82e5-bd521faba28d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019e043c-ca40-7dea-82e5-bd521faba28d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e043c-ca40-7e94-b545-afae05c5b343" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-7aa0-ae2b-bb2884cbf813" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e043c-ca40-7e94-b545-afae05c5b343" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsActivityTableDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#EquityAwardsRestrictedStockUnitsActivityTableDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityAwardsRestrictedStockUnitsActivityTableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-752c-9fee-77273979fdbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-73d4-b602-d6c96ccc3d06" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-752c-9fee-77273979fdbf" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-73d4-b602-d6c96ccc3d06" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7cb8-a1b9-d1df80355387" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019e043c-ca40-73d4-b602-d6c96ccc3d06" xlink:to="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7cb8-a1b9-d1df80355387" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7cb8-a1b9-d1df80355387_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7cb8-a1b9-d1df80355387" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7cb8-a1b9-d1df80355387_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7fdb-91f3-b2a1c20c6441" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7cb8-a1b9-d1df80355387" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7fdb-91f3-b2a1c20c6441" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-7a17-bdde-e88a4f205d0f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7fdb-91f3-b2a1c20c6441" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-7a17-bdde-e88a4f205d0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e043c-ca40-7dff-b40e-8311871bc6bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-752c-9fee-77273979fdbf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e043c-ca40-7dff-b40e-8311871bc6bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e043c-ca40-73b1-84d0-dbf35046577d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e043c-ca40-7dff-b40e-8311871bc6bf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e043c-ca40-73b1-84d0-dbf35046577d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment_019e043c-ca40-7784-b22f-95fe54db83cb" xlink:href="trs-20260630.xsd#trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e043c-ca40-7dff-b40e-8311871bc6bf" xlink:to="loc_trs_SharebasedCompensationArrangementbySharebasedPaymentAwardOtherThanOptionsSpinoffAdjustment_019e043c-ca40-7784-b22f-95fe54db83cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e043c-ca40-7372-9b00-b007f003c6b1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e043c-ca40-7dff-b40e-8311871bc6bf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019e043c-ca40-7372-9b00-b007f003c6b1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e043c-ca40-72e4-b92a-e9140256b8e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e043c-ca40-7dff-b40e-8311871bc6bf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019e043c-ca40-72e4-b92a-e9140256b8e7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e043c-ca40-7371-b42c-24becd867493" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_019e043c-ca40-7dff-b40e-8311871bc6bf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019e043c-ca40-7371-b42c-24becd867493" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019e043c-ca40-7f66-9ead-e0060951ecdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e043c-ca40-723f-83fb-64d72f4c0f56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-752c-9fee-77273979fdbf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e043c-ca40-723f-83fb-64d72f4c0f56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e043c-ca40-7434-aae5-f9344e9d5d4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e043c-ca40-723f-83fb-64d72f4c0f56" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e043c-ca40-7434-aae5-f9344e9d5d4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e043c-ca40-72b3-8aef-f9e2fbed9ae1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e043c-ca40-723f-83fb-64d72f4c0f56" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019e043c-ca40-72b3-8aef-f9e2fbed9ae1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e043c-ca40-77fc-a893-9303141f36c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e043c-ca40-723f-83fb-64d72f4c0f56" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019e043c-ca40-77fc-a893-9303141f36c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e043c-ca40-7d1e-aa92-689a69715b53" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019e043c-ca40-723f-83fb-64d72f4c0f56" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019e043c-ca40-7d1e-aa92-689a69715b53" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019e043c-ca40-7f70-8342-6b5bd7a48529" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e043c-ca40-7469-995c-82b1cf460ba2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019e043c-ca40-752c-9fee-77273979fdbf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e043c-ca40-7469-995c-82b1cf460ba2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_019e043c-ca40-7ac8-8c6a-6468f6ce6c45" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e043c-ca40-7469-995c-82b1cf460ba2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_019e043c-ca40-7ac8-8c6a-6468f6ce6c45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_019e043c-ca40-7071-b141-f3b986963e36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAdditionalDisclosuresAbstract_019e043c-ca40-7469-995c-82b1cf460ba2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedIntrinsicValue_019e043c-ca40-7071-b141-f3b986963e36" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsperShareEarningsperShareDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#EarningsperShareEarningsperShareDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsperShareEarningsperShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDilutedLineItems_019e043c-ca40-739e-a417-4f6175326b47" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDilutedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019e043c-ca40-705d-9eb6-7d59bed8b808" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019e043c-ca40-739e-a417-4f6175326b47" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019e043c-ca40-705d-9eb6-7d59bed8b808" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7d6c-81a3-9eff3a1198d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareDilutedByCommonClassTable_019e043c-ca40-705d-9eb6-7d59bed8b808" xlink:to="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7d6c-81a3-9eff3a1198d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7d6c-81a3-9eff3a1198d4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7d6c-81a3-9eff3a1198d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7d6c-81a3-9eff3a1198d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7265-bc54-355a1fd56a12" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019e043c-ca40-7d6c-81a3-9eff3a1198d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7265-bc54-355a1fd56a12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-74ef-86c4-99a609cd4a14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7265-bc54-355a1fd56a12" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019e043c-ca40-74ef-86c4-99a609cd4a14" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-7069-a0c6-d9afb4e5ef83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019e043c-ca40-7265-bc54-355a1fd56a12" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019e043c-ca40-7069-a0c6-d9afb4e5ef83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e043c-ca40-7dfc-9ae0-dc49941f11df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019e043c-ca40-739e-a417-4f6175326b47" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e043c-ca40-7dfc-9ae0-dc49941f11df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e043c-ca40-7016-81a7-d50df527ab64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019e043c-ca40-739e-a417-4f6175326b47" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e043c-ca40-7016-81a7-d50df527ab64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e043c-ca40-75fc-b101-b17443a60206" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019e043c-ca40-739e-a417-4f6175326b47" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e043c-ca40-75fc-b101-b17443a60206" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e043c-ca40-7919-ba55-9b4b84ed50a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareDilutedLineItems_019e043c-ca40-739e-a417-4f6175326b47" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019e043c-ca40-7919-ba55-9b4b84ed50a5" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EarningsperShareRepurchaseofCommonStockDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#EarningsperShareRepurchaseofCommonStockDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EarningsperShareRepurchaseofCommonStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019e043c-ca40-72d9-857a-f9fbe9e16655" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramTable_019e043c-ca40-7366-82da-b34c0d0c124a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ShareRepurchaseProgramTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019e043c-ca40-72d9-857a-f9fbe9e16655" xlink:to="loc_srt_ShareRepurchaseProgramTable_019e043c-ca40-7366-82da-b34c0d0c124a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramAxis_019e043c-ca40-7c13-9e8c-ed1e0604a12e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ShareRepurchaseProgramTable_019e043c-ca40-7366-82da-b34c0d0c124a" xlink:to="loc_srt_ShareRepurchaseProgramAxis_019e043c-ca40-7c13-9e8c-ed1e0604a12e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_019e043c-ca40-7c13-9e8c-ed1e0604a12e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ShareRepurchaseProgramAxis_019e043c-ca40-7c13-9e8c-ed1e0604a12e" xlink:to="loc_srt_ShareRepurchaseProgramDomain_019e043c-ca40-7c13-9e8c-ed1e0604a12e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_019e043c-ca40-7639-9bad-78e72a28ae3f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ShareRepurchaseProgramAxis_019e043c-ca40-7c13-9e8c-ed1e0604a12e" xlink:to="loc_srt_ShareRepurchaseProgramDomain_019e043c-ca40-7639-9bad-78e72a28ae3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_A10b51sharerepurchaseprogramMember_019e043c-ca40-7ab4-839e-77058cd75f67" xlink:href="trs-20260630.xsd#trs_A10b51sharerepurchaseprogramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ShareRepurchaseProgramDomain_019e043c-ca40-7639-9bad-78e72a28ae3f" xlink:to="loc_trs_A10b51sharerepurchaseprogramMember_019e043c-ca40-7ab4-839e-77058cd75f67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019e043c-ca40-7e81-a0bc-021b5652d92e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-ca40-72d9-857a-f9fbe9e16655" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019e043c-ca40-7e81-a0bc-021b5652d92e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019e043c-ca40-7310-861c-2478c1148947" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-ca40-72d9-857a-f9fbe9e16655" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019e043c-ca40-7310-861c-2478c1148947" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019e043c-ca40-795a-a05d-69027071726b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-ca40-72d9-857a-f9fbe9e16655" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019e043c-ca40-795a-a05d-69027071726b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019e043c-ca40-7c98-a122-2daabb4376ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019e043c-ca40-72d9-857a-f9fbe9e16655" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019e043c-ca40-7c98-a122-2daabb4376ae" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlansNetPeriodicPensionCostsDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DefinedBenefitPlansNetPeriodicPensionCostsDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlansNetPeriodicPensionCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019e043c-ca40-7ff4-8064-2aafb89143e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019e043c-ca40-7ff4-8064-2aafb89143e6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-78ad-83a5-ff5e0cd88e04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019e043c-ca40-7ff4-8064-2aafb89143e6" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-78ad-83a5-ff5e0cd88e04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-78ad-83a5-ff5e0cd88e04_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-78ad-83a5-ff5e0cd88e04" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-78ad-83a5-ff5e0cd88e04_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-706f-a7ea-d1c1b087ef5c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-78ad-83a5-ff5e0cd88e04" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-706f-a7ea-d1c1b087ef5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019e043c-ca40-7fd3-95f7-06004553139f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-706f-a7ea-d1c1b087ef5c" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019e043c-ca40-7fd3-95f7-06004553139f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e043c-ca40-7e69-a063-7f168b506c88" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-706f-a7ea-d1c1b087ef5c" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_019e043c-ca40-7e69-a063-7f168b506c88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7132-8481-e524dfcdb525" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_019e043c-ca40-7ff4-8064-2aafb89143e6" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7132-8481-e524dfcdb525" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7132-8481-e524dfcdb525_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7132-8481-e524dfcdb525" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7132-8481-e524dfcdb525_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7807-8ddf-d75eeec6de41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019e043c-ca40-7132-8481-e524dfcdb525" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7807-8ddf-d75eeec6de41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_019e043c-ca40-736b-9f24-e0b9ddbc496c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019e043c-ca40-7807-8ddf-d75eeec6de41" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_019e043c-ca40-736b-9f24-e0b9ddbc496c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_019e043c-ca40-721b-9222-e0279cad883a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_019e043c-ca40-721b-9222-e0279cad883a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_019e043c-ca40-7775-8adf-3d8536b219d1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_019e043c-ca40-7775-8adf-3d8536b219d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019e043c-ca40-7408-b851-189b42a3552a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_019e043c-ca40-7408-b851-189b42a3552a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019e043c-ca40-7dc3-b0ac-fd9e7933e029" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_019e043c-ca40-7dc3-b0ac-fd9e7933e029" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019e043c-ca40-70d7-970e-5410df2c3128" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019e043c-ca40-70d7-970e-5410df2c3128" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019e043c-ca40-725d-87e2-9ad1c13b497a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_019e043c-ca40-725d-87e2-9ad1c13b497a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e043c-ca40-729c-8d43-3b93e14852f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_019e043c-ca40-78c1-87db-f5136ea2329c" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_019e043c-ca40-729c-8d43-3b93e14852f9" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/DefinedBenefitPlansDefinedBenefitPlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e043c-ca40-72ba-ac15-92cdbd58e22e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e043c-ca40-7c7d-af17-0ac1db77b716" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e043c-ca40-72ba-ac15-92cdbd58e22e" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e043c-ca40-7c7d-af17-0ac1db77b716" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-715c-ae20-1c7051f64978" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e043c-ca40-7c7d-af17-0ac1db77b716" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-715c-ae20-1c7051f64978" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-715c-ae20-1c7051f64978_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-715c-ae20-1c7051f64978" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-715c-ae20-1c7051f64978_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-7910-b97c-d81112760aac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_019e043c-ca40-715c-ae20-1c7051f64978" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-7910-b97c-d81112760aac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_019e043c-ca40-7d5b-be37-03c7658d572a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_019e043c-ca40-7910-b97c-d81112760aac" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_019e043c-ca40-7d5b-be37-03c7658d572a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationAxis_019e043c-ca40-7de8-a1cd-c1538df7cb60" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanSponsorLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_019e043c-ca40-7c7d-af17-0ac1db77b716" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationAxis_019e043c-ca40-7de8-a1cd-c1538df7cb60" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_019e043c-ca40-7de8-a1cd-c1538df7cb60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_019e043c-ca40-7de8-a1cd-c1538df7cb60" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_019e043c-ca40-7de8-a1cd-c1538df7cb60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanSponsorLocationDomain_019e043c-ca40-79a7-8dca-f734e3e11d4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetirementPlanSponsorLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationAxis_019e043c-ca40-7de8-a1cd-c1538df7cb60" xlink:to="loc_us-gaap_RetirementPlanSponsorLocationDomain_019e043c-ca40-79a7-8dca-f734e3e11d4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignPlanMember_019e043c-ca40-71fd-82e4-d75f9c2d1aac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanSponsorLocationDomain_019e043c-ca40-79a7-8dca-f734e3e11d4f" xlink:to="loc_us-gaap_ForeignPlanMember_019e043c-ca40-71fd-82e4-d75f9c2d1aac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_019e043c-ca40-7ec4-a6a6-7b682a800eee" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignPlanMember_019e043c-ca40-71fd-82e4-d75f9c2d1aac" xlink:to="loc_country_GB_019e043c-ca40-7ec4-a6a6-7b682a800eee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019e043c-ca40-7945-a4b9-6d1d3f110605" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e043c-ca40-72ba-ac15-92cdbd58e22e" xlink:to="loc_us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1_019e043c-ca40-7945-a4b9-6d1d3f110605" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_019e043c-ca40-7bb2-bd41-b613f61ce561" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e043c-ca40-72ba-ac15-92cdbd58e22e" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_019e043c-ca40-7bb2-bd41-b613f61ce561" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_019e043c-ca40-7048-8bb6-9b21de279898" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_019e043c-ca40-72ba-ac15-92cdbd58e22e" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear_019e043c-ca40-7048-8bb6-9b21de279898" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/EquityOfferingDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#EquityOfferingDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/EquityOfferingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_019e043c-ca40-7f44-9a60-09cf4b45b742" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_019e043c-ca40-7d0b-897b-aae5f311b53b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e043c-ca40-7f44-9a60-09cf4b45b742" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_019e043c-ca40-7d0b-897b-aae5f311b53b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019e043c-ca40-7c6e-9f7a-050989052e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_019e043c-ca40-7d0b-897b-aae5f311b53b" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019e043c-ca40-7c6e-9f7a-050989052e9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e043c-ca40-7c6e-9f7a-050989052e9f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e043c-ca40-7c6e-9f7a-050989052e9f" xlink:to="loc_us-gaap_ClassOfStockDomain_019e043c-ca40-7c6e-9f7a-050989052e9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019e043c-ca40-705e-b249-b81679535766" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019e043c-ca40-7c6e-9f7a-050989052e9f" xlink:to="loc_us-gaap_ClassOfStockDomain_019e043c-ca40-705e-b249-b81679535766" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019e043c-ca40-74f7-a576-16ca647087d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019e043c-ca40-705e-b249-b81679535766" xlink:to="loc_us-gaap_CommonStockMember_019e043c-ca40-74f7-a576-16ca647087d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019e043c-ca40-7258-ae10-1e9075b699e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e043c-ca40-7f44-9a60-09cf4b45b742" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_019e043c-ca40-7258-ae10-1e9075b699e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_019e043c-ca40-73ed-82d7-b02097eaf3cf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e043c-ca40-7f44-9a60-09cf4b45b742" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_019e043c-ca40-73ed-82d7-b02097eaf3cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_019e043c-ca40-7514-96ed-cd667a0af052" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e043c-ca40-7f44-9a60-09cf4b45b742" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_019e043c-ca40-7514-96ed-cd667a0af052" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019e043c-ca40-75ca-9e57-d893ef9f4c07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019e043c-ca40-7f44-9a60-09cf4b45b742" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019e043c-ca40-75ca-9e57-d893ef9f4c07" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#OtherComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/OtherComprehensiveIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e043c-ca40-771f-af11-13b88de2019c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e043c-ca40-7293-8ee6-3b2f650bca99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e043c-ca40-771f-af11-13b88de2019c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e043c-ca40-7293-8ee6-3b2f650bca99" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019e043c-ca40-7728-9e05-680599e5693f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e043c-ca40-7293-8ee6-3b2f650bca99" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019e043c-ca40-7728-9e05-680599e5693f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7728-9e05-680599e5693f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e043c-ca40-7728-9e05-680599e5693f" xlink:to="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7728-9e05-680599e5693f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7c72-9f99-d78cbbad6688" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019e043c-ca40-7728-9e05-680599e5693f" xlink:to="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7c72-9f99-d78cbbad6688" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e043c-ca40-72ef-944b-0c29c3079489" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7c72-9f99-d78cbbad6688" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019e043c-ca40-72ef-944b-0c29c3079489" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember_019e043c-ca40-7e04-b8c9-877ad6787148" xlink:href="trs-20260630.xsd#trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7c72-9f99-d78cbbad6688" xlink:to="loc_trs_AccumulatedNetGainLossfromHedgesAttributabletoParentMember_019e043c-ca40-7e04-b8c9-877ad6787148" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e043c-ca40-7a10-a6a5-8ed646f3af99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7c72-9f99-d78cbbad6688" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019e043c-ca40-7a10-a6a5-8ed646f3af99" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e043c-ca40-7b2f-821c-9ec6a4ec3580" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019e043c-ca40-7c72-9f99-d78cbbad6688" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019e043c-ca40-7b2f-821c-9ec6a4ec3580" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca40-7e64-86b8-57ecc3d1fad5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019e043c-ca40-7293-8ee6-3b2f650bca99" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca40-7e64-86b8-57ecc3d1fad5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-7e64-86b8-57ecc3d1fad5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca40-7e64-86b8-57ecc3d1fad5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-7e64-86b8-57ecc3d1fad5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-75b0-83b5-e5dc121fddc0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-ca40-7e64-86b8-57ecc3d1fad5" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-75b0-83b5-e5dc121fddc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca40-7976-b4da-b8b80ab74023" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-ca40-75b0-83b5-e5dc121fddc0" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-ca40-7976-b4da-b8b80ab74023" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e043c-ca40-7f0c-96d0-572c4c171d61" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e043c-ca40-771f-af11-13b88de2019c" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e043c-ca40-7f0c-96d0-572c4c171d61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e043c-ca40-7224-a170-cd52acc78891" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e043c-ca40-7f0c-96d0-572c4c171d61" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e043c-ca40-7224-a170-cd52acc78891" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e043c-ca40-72e5-a469-f9a2e0b38062" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e043c-ca40-7f0c-96d0-572c4c171d61" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019e043c-ca40-72e5-a469-f9a2e0b38062" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca40-768d-9e13-cc7cf472212f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e043c-ca40-7f0c-96d0-572c4c171d61" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019e043c-ca40-768d-9e13-cc7cf472212f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e043c-ca40-75b1-a6a1-1c016a8da615" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e043c-ca40-7f0c-96d0-572c4c171d61" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019e043c-ca40-75b1-a6a1-1c016a8da615" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_Reclassificationofstrandedtaxeffects_019e043c-ca40-78ab-98b0-e222c5522f26" xlink:href="trs-20260630.xsd#trs_Reclassificationofstrandedtaxeffects"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019e043c-ca40-7f0c-96d0-572c4c171d61" xlink:to="loc_trs_Reclassificationofstrandedtaxeffects_019e043c-ca40-78ab-98b0-e222c5522f26" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019e043c-ca40-7966-b443-81a7359527d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_019e043c-ca40-7f29-8b4a-52aad1c6b27e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e043c-ca40-771f-af11-13b88de2019c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxAbstract_019e043c-ca40-7f29-8b4a-52aad1c6b27e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTax_019e043c-ca40-785c-b186-e30d0cd9c383" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e043c-ca40-771f-af11-13b88de2019c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTax_019e043c-ca40-785c-b186-e30d0cd9c383" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax_019e043c-ca40-71f4-bc5e-ee3fc8d71100" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e043c-ca40-771f-af11-13b88de2019c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBeforeReclassificationAdjustmentsTax_019e043c-ca40-71f4-bc5e-ee3fc8d71100" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax_019e043c-ca40-7570-9368-b16c830c2781" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019e043c-ca40-771f-af11-13b88de2019c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax_019e043c-ca40-7570-9368-b16c830c2781" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019e043c-ca40-7615-bc01-074c9a16bd00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019e043c-ca40-7369-a50c-845f579795e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019e043c-ca40-7615-bc01-074c9a16bd00" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019e043c-ca40-7369-a50c-845f579795e6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-7d2b-99ba-2cf4c02152a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019e043c-ca40-7369-a50c-845f579795e6" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-7d2b-99ba-2cf4c02152a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-7d2b-99ba-2cf4c02152a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-7d2b-99ba-2cf4c02152a3" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-7d2b-99ba-2cf4c02152a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-7164-b6d8-b92ff0ea2b3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_019e043c-ca40-7d2b-99ba-2cf4c02152a3" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-7164-b6d8-b92ff0ea2b3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ArrowEngineMember_019e043c-ca40-721c-bc10-092f9531c783" xlink:href="trs-20260630.xsd#trs_ArrowEngineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_019e043c-ca40-7164-b6d8-b92ff0ea2b3b" xlink:to="loc_trs_ArrowEngineMember_019e043c-ca40-721c-bc10-092f9531c783" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e043c-ca40-7a68-8e7b-a2ad201afa9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019e043c-ca40-7615-bc01-074c9a16bd00" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e043c-ca40-7a68-8e7b-a2ad201afa9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_ReclassificationOfDeferredTaxBenefitsAerospaceDivestiture_019e043c-ca40-7d76-b656-c4d07a569e1a" xlink:href="trs-20260630.xsd#trs_ReclassificationOfDeferredTaxBenefitsAerospaceDivestiture"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019e043c-ca40-7615-bc01-074c9a16bd00" xlink:to="loc_trs_ReclassificationOfDeferredTaxBenefitsAerospaceDivestiture_019e043c-ca40-7d76-b656-c4d07a569e1a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventDividendDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#SubsequentEventDividendDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventDividendDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7c84-abfb-fa6d76e9122c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019e043c-ca40-7001-b916-d9fbba1e5198" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7c84-abfb-fa6d76e9122c" xlink:to="loc_us-gaap_SubsequentEventTable_019e043c-ca40-7001-b916-d9fbba1e5198" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019e043c-ca40-722d-aac9-ba835e6bacc3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-ca40-7001-b916-d9fbba1e5198" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019e043c-ca40-722d-aac9-ba835e6bacc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-ca40-722d-aac9-ba835e6bacc3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-ca40-722d-aac9-ba835e6bacc3" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-ca40-722d-aac9-ba835e6bacc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-ca40-7e91-8e35-7656c3201a14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-ca40-722d-aac9-ba835e6bacc3" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-ca40-7e91-8e35-7656c3201a14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019e043c-ca40-7102-b868-fb472fe0ddee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019e043c-ca40-7e91-8e35-7656c3201a14" xlink:to="loc_us-gaap_SubsequentEventMember_019e043c-ca40-7102-b868-fb472fe0ddee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsAxis_019e043c-ca40-7ee2-9efb-6ee86ed9b4a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-ca40-7001-b916-d9fbba1e5198" xlink:to="loc_us-gaap_DividendsAxis_019e043c-ca40-7ee2-9efb-6ee86ed9b4a1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019e043c-ca40-7ee2-9efb-6ee86ed9b4a1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DividendsAxis_019e043c-ca40-7ee2-9efb-6ee86ed9b4a1" xlink:to="loc_us-gaap_DividendsDomain_019e043c-ca40-7ee2-9efb-6ee86ed9b4a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDomain_019e043c-ca40-7fd4-8537-e5959d4dc5eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DividendsAxis_019e043c-ca40-7ee2-9efb-6ee86ed9b4a1" xlink:to="loc_us-gaap_DividendsDomain_019e043c-ca40-7fd4-8537-e5959d4dc5eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_O2025Q2DividendsMember_019e043c-ca40-7911-8382-d425f949436d" xlink:href="trs-20260630.xsd#trs_O2025Q2DividendsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsDomain_019e043c-ca40-7fd4-8537-e5959d4dc5eb" xlink:to="loc_trs_O2025Q2DividendsMember_019e043c-ca40-7911-8382-d425f949436d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_O2026Q3DividendsMember_019e043c-caf5-7214-bcb7-f0c74990451d" xlink:href="trs-20260630.xsd#trs_O2026Q3DividendsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DividendsDomain_019e043c-ca40-7fd4-8537-e5959d4dc5eb" xlink:to="loc_trs_O2026Q3DividendsMember_019e043c-caf5-7214-bcb7-f0c74990451d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableAmountPerShare_019e043c-caf5-7682-911e-0ecfef6b38c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPayableAmountPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7c84-abfb-fa6d76e9122c" xlink:to="loc_us-gaap_DividendsPayableAmountPerShare_019e043c-caf5-7682-911e-0ecfef6b38c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_019e043c-caf5-74d2-8728-5d34d8ead8e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPayableDateDeclaredDayMonthAndYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7c84-abfb-fa6d76e9122c" xlink:to="loc_us-gaap_DividendsPayableDateDeclaredDayMonthAndYear_019e043c-caf5-74d2-8728-5d34d8ead8e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendPayableDateToBePaidDayMonthAndYear_019e043c-caf5-762e-9572-7a232829a37e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendPayableDateToBePaidDayMonthAndYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7c84-abfb-fa6d76e9122c" xlink:to="loc_us-gaap_DividendPayableDateToBePaidDayMonthAndYear_019e043c-caf5-762e-9572-7a232829a37e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_019e043c-caf5-7fed-a1b6-50a6db4fe4e1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DividendsPayableDateOfRecordDayMonthAndYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7c84-abfb-fa6d76e9122c" xlink:to="loc_us-gaap_DividendsPayableDateOfRecordDayMonthAndYear_019e043c-caf5-7fed-a1b6-50a6db4fe4e1" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventCrossCurrencySwapDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#SubsequentEventCrossCurrencySwapDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventCrossCurrencySwapDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-77b0-8680-2393154f9259" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019e043c-caf5-7f80-8141-402d6d2657ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-77b0-8680-2393154f9259" xlink:to="loc_us-gaap_SubsequentEventTable_019e043c-caf5-7f80-8141-402d6d2657ff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-caf5-7b24-88d2-a3b4b796df00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-caf5-7f80-8141-402d6d2657ff" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-caf5-7b24-88d2-a3b4b796df00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-caf5-7b24-88d2-a3b4b796df00_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-caf5-7b24-88d2-a3b4b796df00" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-caf5-7b24-88d2-a3b4b796df00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019e043c-caf5-7d43-b8ff-7044d03b5ab1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019e043c-caf5-7b24-88d2-a3b4b796df00" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019e043c-caf5-7d43-b8ff-7044d03b5ab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-caf5-70d6-9921-ae676c4c8fa0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CrossCurrencyInterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019e043c-caf5-7d43-b8ff-7044d03b5ab1" xlink:to="loc_us-gaap_CrossCurrencyInterestRateContractMember_019e043c-caf5-70d6-9921-ae676c4c8fa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-caf5-77b0-a35a-f194e139e0c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-caf5-7f80-8141-402d6d2657ff" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-caf5-77b0-a35a-f194e139e0c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-caf5-77b0-a35a-f194e139e0c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-caf5-77b0-a35a-f194e139e0c6" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-caf5-77b0-a35a-f194e139e0c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019e043c-caf5-7c1a-aad2-2bbf64ca001c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019e043c-caf5-77b0-a35a-f194e139e0c6" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019e043c-caf5-7c1a-aad2-2bbf64ca001c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019e043c-caf5-756a-92cc-68b7f41682b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019e043c-caf5-7c1a-aad2-2bbf64ca001c" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019e043c-caf5-756a-92cc-68b7f41682b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7556-ba6b-0409975fa13d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-caf5-7f80-8141-402d6d2657ff" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7556-ba6b-0409975fa13d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7556-ba6b-0409975fa13d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7556-ba6b-0409975fa13d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7556-ba6b-0409975fa13d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7840-a44a-bb7054bc9333" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7556-ba6b-0409975fa13d" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7840-a44a-bb7054bc9333" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019e043c-caf5-759f-bed0-1a03c77f1603" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7840-a44a-bb7054bc9333" xlink:to="loc_us-gaap_SubsequentEventMember_019e043c-caf5-759f-bed0-1a03c77f1603" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_DerivativeNotionalAmountToBeSettled_019e043c-caf5-72b3-9723-e4faea6fba7a" xlink:href="trs-20260630.xsd#trs_DerivativeNotionalAmountToBeSettled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-77b0-8680-2393154f9259" xlink:to="loc_trs_DerivativeNotionalAmountToBeSettled_019e043c-caf5-72b3-9723-e4faea6fba7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019e043c-caf5-717d-9dc5-b20a44d18cd9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-77b0-8680-2393154f9259" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019e043c-caf5-717d-9dc5-b20a44d18cd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFixedInterestRate_019e043c-caf5-79e4-9355-919a0ffa8c11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFixedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-77b0-8680-2393154f9259" xlink:to="loc_us-gaap_DerivativeFixedInterestRate_019e043c-caf5-79e4-9355-919a0ffa8c11" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_CashProceedsExpectedOnSettlementOfDerivative_019e043c-caf5-708e-9c1d-e119b5643d0d" xlink:href="trs-20260630.xsd#trs_CashProceedsExpectedOnSettlementOfDerivative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-77b0-8680-2393154f9259" xlink:to="loc_trs_CashProceedsExpectedOnSettlementOfDerivative_019e043c-caf5-708e-9c1d-e119b5643d0d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventSaleofPropertyDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#SubsequentEventSaleofPropertyDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventSaleofPropertyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7aad-a269-41601e7d61a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019e043c-caf5-773f-aa41-831866220272" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7aad-a269-41601e7d61a1" xlink:to="loc_us-gaap_SubsequentEventTable_019e043c-caf5-773f-aa41-831866220272" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-73c3-bf7e-422f74afae92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-caf5-773f-aa41-831866220272" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-73c3-bf7e-422f74afae92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-73c3-bf7e-422f74afae92_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-73c3-bf7e-422f74afae92" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-73c3-bf7e-422f74afae92_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-70e4-9ef0-503ddd332628" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-73c3-bf7e-422f74afae92" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-70e4-9ef0-503ddd332628" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019e043c-caf5-7acd-b494-f219c50ac23f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-70e4-9ef0-503ddd332628" xlink:to="loc_us-gaap_SubsequentEventMember_019e043c-caf5-7acd-b494-f219c50ac23f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_019e043c-caf5-78ed-b92b-928ca03ee8e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7aad-a269-41601e7d61a1" xlink:to="loc_us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment_019e043c-caf5-78ed-b92b-928ca03ee8e0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.trimascorp.com/role/SubsequentEventWeldmacDetails" xlink:type="simple" xlink:href="trs-20260630.xsd#SubsequentEventWeldmacDetails"/>
  <link:definitionLink xlink:role="http://www.trimascorp.com/role/SubsequentEventWeldmacDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7f78-ab59-e1558025c359" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019e043c-caf5-76af-86e1-e0f6826c4aa5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7f78-ab59-e1558025c359" xlink:to="loc_us-gaap_SubsequentEventTable_019e043c-caf5-76af-86e1-e0f6826c4aa5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7e60-9519-4efdfdfb620a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-caf5-76af-86e1-e0f6826c4aa5" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7e60-9519-4efdfdfb620a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7e60-9519-4efdfdfb620a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7e60-9519-4efdfdfb620a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7e60-9519-4efdfdfb620a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7d31-9fcb-6bbfa63f8955" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019e043c-caf5-7e60-9519-4efdfdfb620a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7d31-9fcb-6bbfa63f8955" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019e043c-caf5-72e1-9f1e-edc00497f8bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019e043c-caf5-7d31-9fcb-6bbfa63f8955" xlink:to="loc_us-gaap_SubsequentEventMember_019e043c-caf5-72e1-9f1e-edc00497f8bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019e043c-caf5-7522-a8c4-f5c8f3027972" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019e043c-caf5-76af-86e1-e0f6826c4aa5" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019e043c-caf5-7522-a8c4-f5c8f3027972" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-caf5-7522-a8c4-f5c8f3027972_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e043c-caf5-7522-a8c4-f5c8f3027972" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-caf5-7522-a8c4-f5c8f3027972_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-caf5-700a-975c-748f53ebdff1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019e043c-caf5-7522-a8c4-f5c8f3027972" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-caf5-700a-975c-748f53ebdff1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_trs_WeldmacManufacturingCompanyMember_019e043c-caf5-7827-afa9-3625ad00fb7b" xlink:href="trs-20260630.xsd#trs_WeldmacManufacturingCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019e043c-caf5-700a-975c-748f53ebdff1" xlink:to="loc_trs_WeldmacManufacturingCompanyMember_019e043c-caf5-7827-afa9-3625ad00fb7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventsDate_019e043c-caf5-7752-bd0a-b9149e6cd46b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventsDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7f78-ab59-e1558025c359" xlink:to="loc_us-gaap_SubsequentEventsDate_019e043c-caf5-7752-bd0a-b9149e6cd46b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e043c-caf5-784e-b14c-94e621605b70" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019e043c-caf5-7f78-ab59-e1558025c359" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019e043c-caf5-784e-b14c-94e621605b70" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
