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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f193b-e4df-77eb-8899-ee53d911fc25,g:c4c3a022-89eb-4d80-a5cd-e17b471d97d2-->
<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.bostonscientific.com/role/CoverDocument" xlink:type="simple" xlink:href="bsx-20260630.xsd#CoverDocument"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/CoverDocument" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInformationLineItems_019f193b-e669-7472-9186-45284d30d9df" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitiesTable_019f193b-e669-7206-aaf5-36e35f1154e5" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntitiesTable_019f193b-e669-7206-aaf5-36e35f1154e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019f193b-e669-70ab-90c8-e20f337fd534" 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_dei_EntitiesTable_019f193b-e669-7206-aaf5-36e35f1154e5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019f193b-e669-70ab-90c8-e20f337fd534" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f193b-e669-70ab-90c8-e20f337fd534_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_019f193b-e669-70ab-90c8-e20f337fd534" xlink:to="loc_us-gaap_ClassOfStockDomain_019f193b-e669-70ab-90c8-e20f337fd534_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f193b-e669-75ef-9fab-59a1f0480b4f" 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_019f193b-e669-70ab-90c8-e20f337fd534" xlink:to="loc_us-gaap_ClassOfStockDomain_019f193b-e669-75ef-9fab-59a1f0480b4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f193b-e669-7401-8370-97019bf1e33b" 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_019f193b-e669-75ef-9fab-59a1f0480b4f" xlink:to="loc_us-gaap_CommonStockMember_019f193b-e669-7401-8370-97019bf1e33b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SeniorNotedue2027Member_019f193b-e669-7980-9375-35b729707a33" xlink:href="bsx-20260630.xsd#bsx_SeniorNotedue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f193b-e669-75ef-9fab-59a1f0480b4f" xlink:to="loc_bsx_SeniorNotedue2027Member_019f193b-e669-7980-9375-35b729707a33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_019f193b-e669-7e45-bb17-658e1b2a188c" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_DocumentType_019f193b-e669-7e45-bb17-658e1b2a188c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_019f193b-e669-7bc6-b291-39767b04e2c5" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_DocumentQuarterlyReport_019f193b-e669-7bc6-b291-39767b04e2c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_019f193b-e669-7ae4-8543-e20f93b658f2" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_DocumentPeriodEndDate_019f193b-e669-7ae4-8543-e20f93b658f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_019f193b-e669-7268-86fa-eba27466ddd1" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_DocumentTransitionReport_019f193b-e669-7268-86fa-eba27466ddd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_019f193b-e669-7b69-8c5a-79de426945f2" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityFileNumber_019f193b-e669-7b69-8c5a-79de426945f2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_019f193b-e669-7a93-86b4-8f02a260e494" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityRegistrantName_019f193b-e669-7a93-86b4-8f02a260e494" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_019f193b-e669-7f46-b7fc-70f2def5b84e" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityIncorporationStateCountryCode_019f193b-e669-7f46-b7fc-70f2def5b84e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_019f193b-e669-73e4-b65c-01a8a60aa7eb" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityTaxIdentificationNumber_019f193b-e669-73e4-b65c-01a8a60aa7eb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_019f193b-e669-787c-962b-0a6e68ac9208" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityAddressAddressLine1_019f193b-e669-787c-962b-0a6e68ac9208" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_019f193b-e669-7b18-a753-0de5c4af700c" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityAddressCityOrTown_019f193b-e669-7b18-a753-0de5c4af700c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_019f193b-e669-7c86-af52-068557bdb22f" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityAddressStateOrProvince_019f193b-e669-7c86-af52-068557bdb22f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_019f193b-e669-76a7-8706-0d7431db6241" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityAddressPostalZipCode_019f193b-e669-76a7-8706-0d7431db6241" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_019f193b-e669-7975-afbd-ef29fd1b7ccc" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_CityAreaCode_019f193b-e669-7975-afbd-ef29fd1b7ccc" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_019f193b-e669-70be-8f4a-50ffd8ea8f9e" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_LocalPhoneNumber_019f193b-e669-70be-8f4a-50ffd8ea8f9e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_019f193b-e669-7170-b48d-1f54a80591de" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_Security12bTitle_019f193b-e669-7170-b48d-1f54a80591de" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_019f193b-e669-71d3-aec1-ab8bfbcb9aa8" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_TradingSymbol_019f193b-e669-71d3-aec1-ab8bfbcb9aa8" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_019f193b-e669-77ae-9daa-97cd4fcadf42" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_SecurityExchangeName_019f193b-e669-77ae-9daa-97cd4fcadf42" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_019f193b-e669-7caa-8029-c62fe2497fe4" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityCurrentReportingStatus_019f193b-e669-7caa-8029-c62fe2497fe4" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_019f193b-e669-7da6-a4d1-43fc1a220130" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityInteractiveDataCurrent_019f193b-e669-7da6-a4d1-43fc1a220130" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_019f193b-e669-7e59-b1d7-9ddb5a8d98c0" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityFilerCategory_019f193b-e669-7e59-b1d7-9ddb5a8d98c0" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_019f193b-e669-774a-ac46-fdb102d3c548" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntitySmallBusiness_019f193b-e669-774a-ac46-fdb102d3c548" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_019f193b-e669-73c6-888a-08033e1204fb" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityEmergingGrowthCompany_019f193b-e669-73c6-888a-08033e1204fb" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_019f193b-e669-7f8f-bb7d-beb5a546bf44" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityShellCompany_019f193b-e669-7f8f-bb7d-beb5a546bf44" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityListingParValuePerShare_019f193b-e669-72d0-9b3a-1fc25aa58a99" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityListingParValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityInformationLineItems_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityListingParValuePerShare_019f193b-e669-72d0-9b3a-1fc25aa58a99" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_019f193b-e669-78cb-9059-86e7d1ff8ccd" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_019f193b-e669-78cb-9059-86e7d1ff8ccd" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_019f193b-e669-7322-b905-c0919cc4f06a" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_EntityCentralIndexKey_019f193b-e669-7322-b905-c0919cc4f06a" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_019f193b-e669-7489-91f3-9187f7ee6666" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_CurrentFiscalYearEndDate_019f193b-e669-7489-91f3-9187f7ee6666" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_019f193b-e669-72e9-a6c1-f30c37ca4f48" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_DocumentFiscalYearFocus_019f193b-e669-72e9-a6c1-f30c37ca4f48" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_019f193b-e669-798b-92a3-e9679399566d" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_DocumentFiscalPeriodFocus_019f193b-e669-798b-92a3-e9679399566d" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_019f193b-e669-7766-858e-7a0b6fa64aed" 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_019f193b-e669-7472-9186-45284d30d9df" xlink:to="loc_dei_AmendmentFlag_019f193b-e669-7766-858e-7a0b6fa64aed" xlink:type="arc" order="29"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/ConsolidatedStatementsofStockholdersEquityUnaudited" xlink:type="simple" xlink:href="bsx-20260630.xsd#ConsolidatedStatementsofStockholdersEquityUnaudited"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/ConsolidatedStatementsofStockholdersEquityUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f193b-e72a-7990-81a9-794789ccd981" 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_019f193b-e72a-74bf-b57d-1cb1c321cd21" 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_019f193b-e72a-7990-81a9-794789ccd981" xlink:to="loc_us-gaap_StatementTable_019f193b-e72a-74bf-b57d-1cb1c321cd21" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72a-7767-8c52-d6737eeea619" 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_019f193b-e72a-74bf-b57d-1cb1c321cd21" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72a-7767-8c52-d6737eeea619" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7767-8c52-d6737eeea619_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_019f193b-e72a-7767-8c52-d6737eeea619" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7767-8c52-d6737eeea619_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7bc9-856c-aa7b749fc6cc" 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_019f193b-e72a-7767-8c52-d6737eeea619" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7bc9-856c-aa7b749fc6cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_019f193b-e72a-7152-9cd3-63f562e5af98" 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_019f193b-e72a-7bc9-856c-aa7b749fc6cc" xlink:to="loc_us-gaap_ParentMember_019f193b-e72a-7152-9cd3-63f562e5af98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f193b-e72a-7c5e-9cf0-83f196940fa9" 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_019f193b-e72a-7152-9cd3-63f562e5af98" xlink:to="loc_us-gaap_CommonStockMember_019f193b-e72a-7c5e-9cf0-83f196940fa9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_019f193b-e72a-7ed7-bdf5-0742311caef3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019f193b-e72a-7152-9cd3-63f562e5af98" xlink:to="loc_us-gaap_TreasuryStockCommonMember_019f193b-e72a-7ed7-bdf5-0742311caef3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019f193b-e72a-7854-8254-234a5e0356d2" 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_019f193b-e72a-7152-9cd3-63f562e5af98" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019f193b-e72a-7854-8254-234a5e0356d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019f193b-e72a-7df3-a9ce-d9e17b30b4c6" 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_019f193b-e72a-7152-9cd3-63f562e5af98" xlink:to="loc_us-gaap_RetainedEarningsMember_019f193b-e72a-7df3-a9ce-d9e17b30b4c6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f193b-e72a-748e-bd62-f73c1398101e" 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_019f193b-e72a-7152-9cd3-63f562e5af98" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f193b-e72a-748e-bd62-f73c1398101e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019f193b-e72a-7194-8543-d180b154895b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7bc9-856c-aa7b749fc6cc" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019f193b-e72a-7194-8543-d180b154895b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f193b-e72a-7990-81a9-794789ccd981" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019f193b-e72a-7b79-ad59-a17072951cf3" 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_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_CommonStockSharesIssued_019f193b-e72a-7b79-ad59-a17072951cf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease_019f193b-e72a-762c-9c8a-2811820149b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesPeriodIncreaseDecrease_019f193b-e72a-762c-9c8a-2811820149b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019f193b-e72a-7e2e-849b-05427cd06cd1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f193b-e72a-7aa5-862c-eac8c49725e9" 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_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f193b-e72a-7aa5-862c-eac8c49725e9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation_019f193b-e72a-7228-a8e6-d751fe05e183" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation_019f193b-e72a-7228-a8e6-d751fe05e183" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f193b-e72a-7e01-bae3-1f14a8f1daaf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_019f193b-e72a-7e01-bae3-1f14a8f1daaf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_019f193b-e72a-762a-b950-c96e15f6f34e" 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_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_ProfitLoss_019f193b-e72a-762a-b950-c96e15f6f34e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019f193b-e72a-7490-afce-092a47096788" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_019f193b-e72a-7490-afce-092a47096788" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f193b-e72a-7e14-9bfd-c87f35adc816" 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_IncreaseDecreaseInStockholdersEquityRollForward_019f193b-e72a-753f-aa88-f6258c0e677d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f193b-e72a-7e14-9bfd-c87f35adc816" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f193b-e72a-7c80-84ce-3c2051449bc2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsNarrativeDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#AcquisitionsDivestituresandStrategicInvestmentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-77a4-bd9d-558e0a8f4147" 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_019f193b-e72a-708f-81ce-abffbe26e151" 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_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-708f-81ce-abffbe26e151" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-74f9-9e1e-50d3f0da4f02" 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_019f193b-e72a-708f-81ce-abffbe26e151" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-74f9-9e1e-50d3f0da4f02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-74f9-9e1e-50d3f0da4f02_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_019f193b-e72a-74f9-9e1e-50d3f0da4f02" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-74f9-9e1e-50d3f0da4f02_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" 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_019f193b-e72a-74f9-9e1e-50d3f0da4f02" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_PenumbraInc.Member_019f193b-e72a-7d37-ba3c-b0707abc6f58" xlink:href="bsx-20260630.xsd#bsx_PenumbraInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_PenumbraInc.Member_019f193b-e72a-7d37-ba3c-b0707abc6f58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_NaluMedicalMember_019f193b-e72a-7fd6-bd06-c983186b838e" xlink:href="bsx-20260630.xsd#bsx_NaluMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_NaluMedicalMember_019f193b-e72a-7fd6-bd06-c983186b838e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CortexInc.Member_019f193b-e72a-7836-b1b3-a004e1b3666c" xlink:href="bsx-20260630.xsd#bsx_CortexInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_CortexInc.Member_019f193b-e72a-7836-b1b3-a004e1b3666c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_AllBusinessAcquisitionsMember_019f193b-e72a-73de-9bdd-2b14fa310892" xlink:href="bsx-20260630.xsd#bsx_AllBusinessAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_AllBusinessAcquisitionsMember_019f193b-e72a-73de-9bdd-2b14fa310892" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ScivitaMedicalMember_019f193b-e72a-7bff-8ef2-efcd2d4f8677" xlink:href="bsx-20260630.xsd#bsx_ScivitaMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_ScivitaMedicalMember_019f193b-e72a-7bff-8ef2-efcd2d4f8677" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Other2026AcquisitionsMember_019f95d9-1cd2-7c25-b985-618fba49ee99" xlink:href="bsx-20260630.xsd#bsx_Other2026AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_Other2026AcquisitionsMember_019f95d9-1cd2-7c25-b985-618fba49ee99" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Other2025AcquisitionsMember_019f95d9-9d6c-771d-a30c-1ab2068540d4" xlink:href="bsx-20260630.xsd#bsx_Other2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_Other2025AcquisitionsMember_019f95d9-9d6c-771d-a30c-1ab2068540d4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SoniVieLtdMember_019f95db-3f4d-7910-9059-ea28e3128122" xlink:href="bsx-20260630.xsd#bsx_SoniVieLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_SoniVieLtdMember_019f95db-3f4d-7910-9059-ea28e3128122" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_BoltMedicalInc.Member_019f95e0-1379-76b2-8feb-ca96f258503c" xlink:href="bsx-20260630.xsd#bsx_BoltMedicalInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_BoltMedicalInc.Member_019f95e0-1379-76b2-8feb-ca96f258503c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_AllOther2025AcquisitionsMember_019fa9ad-97d6-738b-a24a-cc121a8dd5a3" xlink:href="bsx-20260630.xsd#bsx_AllOther2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-79aa-b122-ce9f7479170a" xlink:to="loc_bsx_AllOther2025AcquisitionsMember_019fa9ad-97d6-738b-a24a-cc121a8dd5a3" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019f193b-e72a-7eaa-9c3b-802a57d46152" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-708f-81ce-abffbe26e151" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019f193b-e72a-7eaa-9c3b-802a57d46152" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-7eaa-9c3b-802a57d46152_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019f193b-e72a-7eaa-9c3b-802a57d46152" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-7eaa-9c3b-802a57d46152_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-70eb-ac4f-c62c2f48b767" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_019f193b-e72a-7eaa-9c3b-802a57d46152" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-70eb-ac4f-c62c2f48b767" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_NaluMedicalMember_019f193b-e72a-79b2-8ca2-c41002acdd37" xlink:href="bsx-20260630.xsd#bsx_NaluMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-70eb-ac4f-c62c2f48b767" xlink:to="loc_bsx_NaluMedicalMember_019f193b-e72a-79b2-8ca2-c41002acdd37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ScivitaMedicalMember_019f193b-e72a-712d-bac0-d4fb5df69a9f" xlink:href="bsx-20260630.xsd#bsx_ScivitaMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-70eb-ac4f-c62c2f48b767" xlink:to="loc_bsx_ScivitaMedicalMember_019f193b-e72a-712d-bac0-d4fb5df69a9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_BoltMedicalInc.Member_019f95df-3959-7bf3-a26d-bc3a8bcacc6d" xlink:href="bsx-20260630.xsd#bsx_BoltMedicalInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-70eb-ac4f-c62c2f48b767" xlink:to="loc_bsx_BoltMedicalInc.Member_019f95df-3959-7bf3-a26d-bc3a8bcacc6d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SoniVieLtdMember_019fa4b6-842f-747b-b270-c1186fe327fb" xlink:href="bsx-20260630.xsd#bsx_SoniVieLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_019f193b-e72a-70eb-ac4f-c62c2f48b767" xlink:to="loc_bsx_SoniVieLtdMember_019fa4b6-842f-747b-b270-c1186fe327fb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019f193b-e72a-7e49-8801-a522faba2018" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019f193b-e72a-7e49-8801-a522faba2018" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_019f193b-e72a-7645-81fe-065957bba701" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_019f193b-e72a-7645-81fe-065957bba701" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019f193b-e72a-72be-9690-35def76a8791" 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_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019f193b-e72a-72be-9690-35def76a8791" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_019f193b-e72a-74d4-a13d-30d386bfa327" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_019f193b-e72a-74d4-a13d-30d386bfa327" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_019f193b-e72a-736d-937e-5ab2f589b972" 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_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_019f193b-e72a-736d-937e-5ab2f589b972" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019f193b-e72a-7531-8e5c-f438b07cdc98" 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_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019f193b-e72a-7531-8e5c-f438b07cdc98" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_UncappedContingentConsideration_019fa9ca-c033-777b-aea5-5595874d9eef" xlink:href="bsx-20260630.xsd#bsx_UncappedContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_bsx_UncappedContingentConsideration_019fa9ca-c033-777b-aea5-5595874d9eef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_BusinessCombinationPaymentForPortionNotPreviouslyOwned_019fb4bd-44ce-7ce6-88a7-9fa23dca852d" xlink:href="bsx-20260630.xsd#bsx_BusinessCombinationPaymentForPortionNotPreviouslyOwned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-77a4-bd9d-558e0a8f4147" xlink:to="loc_bsx_BusinessCombinationPaymentForPortionNotPreviouslyOwned_019fb4bd-44ce-7ce6-88a7-9fa23dca852d" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsPriceAllocationDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#AcquisitionsDivestituresandStrategicInvestmentsPriceAllocationDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsPriceAllocationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-752d-a1b1-3fbe9ffd9ca9" 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_019f193b-e72a-7946-87a1-a28af6c18e8f" 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_019f193b-e72a-752d-a1b1-3fbe9ffd9ca9" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-7946-87a1-a28af6c18e8f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-7db5-b64e-010069593f93" 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_019f193b-e72a-7946-87a1-a28af6c18e8f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-7db5-b64e-010069593f93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7db5-b64e-010069593f93_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_019f193b-e72a-7db5-b64e-010069593f93" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7db5-b64e-010069593f93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ffb-98bd-f92a4003ab53" 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_019f193b-e72a-7db5-b64e-010069593f93" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ffb-98bd-f92a4003ab53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_NaluMedicalMember_019f193b-e72a-7294-b062-f2fce52d1990" xlink:href="bsx-20260630.xsd#bsx_NaluMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ffb-98bd-f92a4003ab53" xlink:to="loc_bsx_NaluMedicalMember_019f193b-e72a-7294-b062-f2fce52d1990" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CortexInc.Member_019f193b-e72a-7abd-afb7-6b1334da8afb" xlink:href="bsx-20260630.xsd#bsx_CortexInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ffb-98bd-f92a4003ab53" xlink:to="loc_bsx_CortexInc.Member_019f193b-e72a-7abd-afb7-6b1334da8afb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_BoltMedicalInc.Member_019f95e3-4f53-7ae3-be22-24acfc1d879b" xlink:href="bsx-20260630.xsd#bsx_BoltMedicalInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ffb-98bd-f92a4003ab53" xlink:to="loc_bsx_BoltMedicalInc.Member_019f95e3-4f53-7ae3-be22-24acfc1d879b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SoniVieLtdMember_019f95e3-8769-7ebb-af19-7e553b62c44a" xlink:href="bsx-20260630.xsd#bsx_SoniVieLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ffb-98bd-f92a4003ab53" xlink:to="loc_bsx_SoniVieLtdMember_019f95e3-8769-7ebb-af19-7e553b62c44a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Other2025AcquisitionsMember_019f95e4-3415-797d-8c8c-1e86e95bc2ea" xlink:href="bsx-20260630.xsd#bsx_Other2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ffb-98bd-f92a4003ab53" xlink:to="loc_bsx_Other2025AcquisitionsMember_019f95e4-3415-797d-8c8c-1e86e95bc2ea" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019f193b-e72a-7170-ae77-89c40b7a160a" 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_019f193b-e72a-752d-a1b1-3fbe9ffd9ca9" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019f193b-e72a-7170-ae77-89c40b7a160a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_FairValueOfPriorInterest_019f193b-e72a-7963-bea5-ac151f1d0436" xlink:href="bsx-20260630.xsd#bsx_FairValueOfPriorInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-752d-a1b1-3fbe9ffd9ca9" xlink:to="loc_bsx_FairValueOfPriorInterest_019f193b-e72a-7963-bea5-ac151f1d0436" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_FairValueOfContingentConsideration_019f193b-e72a-7a40-8986-d570f355c100" xlink:href="bsx-20260630.xsd#bsx_FairValueOfContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-752d-a1b1-3fbe9ffd9ca9" xlink:to="loc_bsx_FairValueOfContingentConsideration_019f193b-e72a-7a40-8986-d570f355c100" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_019f193b-e72a-7710-863f-8c78323ac0ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-752d-a1b1-3fbe9ffd9ca9" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_019f193b-e72a-7710-863f-8c78323ac0ec" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsAssetsandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#AcquisitionsDivestituresandStrategicInvestmentsAssetsandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsAssetsandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-750f-9b6e-daa42d9efd6b" 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_019f193b-e72a-7e53-83ae-33902a5cb242" 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_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-7e53-83ae-33902a5cb242" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-7e3f-afdc-07dc51f5e87a" 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_019f193b-e72a-7e53-83ae-33902a5cb242" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-7e3f-afdc-07dc51f5e87a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e3f-afdc-07dc51f5e87a_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_019f193b-e72a-7e3f-afdc-07dc51f5e87a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e3f-afdc-07dc51f5e87a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-77ca-b289-7ff744113425" 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_019f193b-e72a-7e3f-afdc-07dc51f5e87a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-77ca-b289-7ff744113425" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_NaluMedicalMember_019f193b-e72a-7ece-8963-bfa09c3ca5af" xlink:href="bsx-20260630.xsd#bsx_NaluMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-77ca-b289-7ff744113425" xlink:to="loc_bsx_NaluMedicalMember_019f193b-e72a-7ece-8963-bfa09c3ca5af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CortexInc.Member_019f193b-e72a-7c77-9a22-4d7f999f1431" xlink:href="bsx-20260630.xsd#bsx_CortexInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-77ca-b289-7ff744113425" xlink:to="loc_bsx_CortexInc.Member_019f193b-e72a-7c77-9a22-4d7f999f1431" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_BoltMedicalInc.Member_019f95e9-05ed-7fad-bd59-cf08c5d8734c" xlink:href="bsx-20260630.xsd#bsx_BoltMedicalInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-77ca-b289-7ff744113425" xlink:to="loc_bsx_BoltMedicalInc.Member_019f95e9-05ed-7fad-bd59-cf08c5d8734c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SoniVieLtdMember_019f95e9-440e-7d3f-af22-d34bf05735e2" xlink:href="bsx-20260630.xsd#bsx_SoniVieLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-77ca-b289-7ff744113425" xlink:to="loc_bsx_SoniVieLtdMember_019f95e9-440e-7d3f-af22-d34bf05735e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Other2025AcquisitionsMember_019f95e9-7e93-74b6-bec0-813a4e74e2be" xlink:href="bsx-20260630.xsd#bsx_Other2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-77ca-b289-7ff744113425" xlink:to="loc_bsx_Other2025AcquisitionsMember_019f95e9-7e93-74b6-bec0-813a4e74e2be" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f193b-e72a-76b8-9865-d561d0f216ee" 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_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_Goodwill_019f193b-e72a-76b8-9865-d561d0f216ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019f193b-e72a-7ce8-a706-288bf8679976" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019f193b-e72a-7ce8-a706-288bf8679976" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets_019f95eb-6e22-7c3f-9262-dc8a7f627b22" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets_019f95eb-6e22-7c3f-9262-dc8a7f627b22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019f193b-e72a-758b-a4f4-f23143c82610" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019f193b-e72a-758b-a4f4-f23143c82610" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets_019f193b-e72a-7963-9dea-32b70e1444eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxAssets_019f193b-e72a-7963-9dea-32b70e1444eb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f193b-e72a-72aa-bad3-16262e35e3ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_019f193b-e72a-72aa-bad3-16262e35e3ec" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019f95ec-4df1-704d-b903-91e7e6ab4650" 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_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019f95ec-4df1-704d-b903-91e7e6ab4650" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_019f193b-e72a-77da-ab90-599ba5bc5e2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-750f-9b6e-daa42d9efd6b" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_019f193b-e72a-77da-ab90-599ba5bc5e2a" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsIntangibleAssetsAcquiredDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#AcquisitionsDivestituresandStrategicInvestmentsIntangibleAssetsAcquiredDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsIntangibleAssetsAcquiredDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-76ad-ba5f-b1e3a5b412d7" 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_019f193b-e72a-7ca7-9f82-355e19d678cf" 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_019f193b-e72a-76ad-ba5f-b1e3a5b412d7" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-7ca7-9f82-355e19d678cf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-7ed0-b4fd-507278d4b237" 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_019f193b-e72a-7ca7-9f82-355e19d678cf" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f193b-e72a-7ed0-b4fd-507278d4b237" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ed0-b4fd-507278d4b237_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_019f193b-e72a-7ed0-b4fd-507278d4b237" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7ed0-b4fd-507278d4b237_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e15-b9e3-b4f20bb2fee7" 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_019f193b-e72a-7ed0-b4fd-507278d4b237" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e15-b9e3-b4f20bb2fee7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_NaluMedicalMember_019f193b-e72a-7641-8700-a06cb2101ddf" xlink:href="bsx-20260630.xsd#bsx_NaluMedicalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e15-b9e3-b4f20bb2fee7" xlink:to="loc_bsx_NaluMedicalMember_019f193b-e72a-7641-8700-a06cb2101ddf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CortexInc.Member_019f193b-e72a-7313-9026-7ecc4444f026" xlink:href="bsx-20260630.xsd#bsx_CortexInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e15-b9e3-b4f20bb2fee7" xlink:to="loc_bsx_CortexInc.Member_019f193b-e72a-7313-9026-7ecc4444f026" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_BoltMedicalInc.Member_019f95ee-50ca-737f-8cc2-ca394b45c1ef" xlink:href="bsx-20260630.xsd#bsx_BoltMedicalInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e15-b9e3-b4f20bb2fee7" xlink:to="loc_bsx_BoltMedicalInc.Member_019f95ee-50ca-737f-8cc2-ca394b45c1ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Other2025AcquisitionsMember_019f95ee-ca1e-7000-a164-e390adffea69" xlink:href="bsx-20260630.xsd#bsx_Other2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e15-b9e3-b4f20bb2fee7" xlink:to="loc_bsx_Other2025AcquisitionsMember_019f95ee-ca1e-7000-a164-e390adffea69" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SoniVieLtdMember_019fa437-719b-7e2d-80bf-3d14c7199bc5" xlink:href="bsx-20260630.xsd#bsx_SoniVieLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f193b-e72a-7e15-b9e3-b4f20bb2fee7" xlink:to="loc_bsx_SoniVieLtdMember_019fa437-719b-7e2d-80bf-3d14c7199bc5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f193b-e72a-71b5-bcbb-c20870415781" 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_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-7ca7-9f82-355e19d678cf" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f193b-e72a-71b5-bcbb-c20870415781" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-71b5-bcbb-c20870415781_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_019f193b-e72a-71b5-bcbb-c20870415781" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-71b5-bcbb-c20870415781_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-707e-9208-94e80094f2d3" 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_019f193b-e72a-71b5-bcbb-c20870415781" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-707e-9208-94e80094f2d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019f193b-e72a-7f70-be5b-d5cb861479eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-707e-9208-94e80094f2d3" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019f193b-e72a-7f70-be5b-d5cb861479eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019f193b-e72a-7bc3-a4d9-74fa3fe64512" 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_019f193b-e72a-707e-9208-94e80094f2d3" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019f193b-e72a-7bc3-a4d9-74fa3fe64512" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019fa435-4dae-7151-af94-4699f267b94a" 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_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-7ca7-9f82-355e19d678cf" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019fa435-4dae-7151-af94-4699f267b94a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fa435-4dae-7151-af94-4699f267b94a_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_019fa435-4dae-7151-af94-4699f267b94a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fa435-4dae-7151-af94-4699f267b94a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fa435-4dae-7536-a831-6bb5b0a3361b" 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_019fa435-4dae-7151-af94-4699f267b94a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fa435-4dae-7536-a831-6bb5b0a3361b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InProcessResearchAndDevelopmentMember_019fa435-74d1-73fe-9c80-a7a81ade0416" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InProcessResearchAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019fa435-4dae-7536-a831-6bb5b0a3361b" xlink:to="loc_us-gaap_InProcessResearchAndDevelopmentMember_019fa435-74d1-73fe-9c80-a7a81ade0416" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019f193b-e72a-7fe1-b9a5-2c533ce3cb54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-76ad-ba5f-b1e3a5b412d7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019f193b-e72a-7fe1-b9a5-2c533ce3cb54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019f193b-e72a-7c86-be47-dd067fb417ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-76ad-ba5f-b1e3a5b412d7" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019f193b-e72a-7c86-be47-dd067fb417ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets_019fa434-1cf0-722d-bcfa-68e1456478bf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-76ad-ba5f-b1e3a5b412d7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIndefiniteLivedIntangibleAssets_019fa434-1cf0-722d-bcfa-68e1456478bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019fa436-5468-7f3b-8599-42d199dbbc04" 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_019f193b-e72a-76ad-ba5f-b1e3a5b412d7" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019fa436-5468-7f3b-8599-42d199dbbc04" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsLevel3ContingentConsiderationDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#AcquisitionsDivestituresandStrategicInvestmentsLevel3ContingentConsiderationDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/AcquisitionsDivestituresandStrategicInvestmentsLevel3ContingentConsiderationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-7ae8-8f17-7efd1e43248d" 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_019f193b-e72a-74f4-9edf-6843f24c5801" 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_019f193b-e72a-7ae8-8f17-7efd1e43248d" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-74f4-9edf-6843f24c5801" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationByTypeAxis_019f193b-e72a-74ae-86cb-fa56a1ccb95c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContingentConsiderationByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-74f4-9edf-6843f24c5801" xlink:to="loc_us-gaap_ContingentConsiderationByTypeAxis_019f193b-e72a-74ae-86cb-fa56a1ccb95c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_019f193b-e72a-74ae-86cb-fa56a1ccb95c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContingentConsiderationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_019f193b-e72a-74ae-86cb-fa56a1ccb95c" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_019f193b-e72a-74ae-86cb-fa56a1ccb95c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_019f193b-e72a-7cf9-9ca8-8a5a23c12746" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContingentConsiderationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_019f193b-e72a-74ae-86cb-fa56a1ccb95c" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_019f193b-e72a-7cf9-9ca8-8a5a23c12746" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RevenueBasedPaymentsMember_019f193b-e72a-78be-9a3f-93587e664820" xlink:href="bsx-20260630.xsd#bsx_RevenueBasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContingentConsiderationTypeDomain_019f193b-e72a-7cf9-9ca8-8a5a23c12746" xlink:to="loc_bsx_RevenueBasedPaymentsMember_019f193b-e72a-78be-9a3f-93587e664820" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RDRegulatoryandCommercializationbasedMilestoneMember_019f193b-e72a-7329-b9e9-f564848d8f38" xlink:href="bsx-20260630.xsd#bsx_RDRegulatoryandCommercializationbasedMilestoneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContingentConsiderationTypeDomain_019f193b-e72a-7cf9-9ca8-8a5a23c12746" xlink:to="loc_bsx_RDRegulatoryandCommercializationbasedMilestoneMember_019f193b-e72a-7329-b9e9-f564848d8f38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_019f193b-e72a-7238-9111-85c53b967f5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-74f4-9edf-6843f24c5801" xlink:to="loc_us-gaap_ValuationTechniqueAxis_019f193b-e72a-7238-9111-85c53b967f5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_019f193b-e72a-7238-9111-85c53b967f5b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_019f193b-e72a-7238-9111-85c53b967f5b" xlink:to="loc_us-gaap_ValuationTechniqueDomain_019f193b-e72a-7238-9111-85c53b967f5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_019f193b-e72a-7d82-ba11-e54e94b210ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_019f193b-e72a-7238-9111-85c53b967f5b" xlink:to="loc_us-gaap_ValuationTechniqueDomain_019f193b-e72a-7d82-ba11-e54e94b210ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_019f193b-e72a-73f9-8ddd-aaf43b4018ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_019f193b-e72a-7d82-ba11-e54e94b210ed" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_019f193b-e72a-73f9-8ddd-aaf43b4018ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f193b-e72a-79a5-9422-0c6ddc8efce1" 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_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019f193b-e72a-74f4-9edf-6843f24c5801" xlink:to="loc_srt_RangeAxis_019f193b-e72a-79a5-9422-0c6ddc8efce1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f193b-e72a-79a5-9422-0c6ddc8efce1_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_019f193b-e72a-79a5-9422-0c6ddc8efce1" xlink:to="loc_srt_RangeMember_019f193b-e72a-79a5-9422-0c6ddc8efce1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f193b-e72a-734f-ae9a-6554b6f7a2fc" 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_019f193b-e72a-79a5-9422-0c6ddc8efce1" xlink:to="loc_srt_RangeMember_019f193b-e72a-734f-ae9a-6554b6f7a2fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f193b-e72a-78ee-823e-7b6313987daa" 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_019f193b-e72a-734f-ae9a-6554b6f7a2fc" xlink:to="loc_srt_MinimumMember_019f193b-e72a-78ee-823e-7b6313987daa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f193b-e72a-7af6-8d6c-db027a686052" 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_019f193b-e72a-734f-ae9a-6554b6f7a2fc" xlink:to="loc_srt_MaximumMember_019f193b-e72a-7af6-8d6c-db027a686052" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember_019f193b-e72a-7b75-b3c5-9a50de363ce4" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_WeightedAverageMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f193b-e72a-734f-ae9a-6554b6f7a2fc" xlink:to="loc_srt_WeightedAverageMember_019f193b-e72a-7b75-b3c5-9a50de363ce4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019f193b-e72a-76e1-8688-8e7824e87e10" 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_019f193b-e72a-7ae8-8f17-7efd1e43248d" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019f193b-e72a-76e1-8688-8e7824e87e10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_DiscountRateFairValueInput_019f193b-e72a-70ad-a41e-ef25cd2faf3d" xlink:href="bsx-20260630.xsd#bsx_DiscountRateFairValueInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-7ae8-8f17-7efd1e43248d" xlink:to="loc_bsx_DiscountRateFairValueInput_019f193b-e72a-70ad-a41e-ef25cd2faf3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ContingentConsiderationLiabilityProbabilityOfPayment_019f193b-e72a-7ccc-ae05-6bfc5ae36920" xlink:href="bsx-20260630.xsd#bsx_ContingentConsiderationLiabilityProbabilityOfPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019f193b-e72a-7ae8-8f17-7efd1e43248d" xlink:to="loc_bsx_ContingentConsiderationLiabilityProbabilityOfPayment_019f193b-e72a-7ccc-ae05-6bfc5ae36920" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/GoodwillandOtherIntangibleAssetsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#GoodwillandOtherIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/GoodwillandOtherIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:href="bsx-20260630.xsd#bsx_IntangibleAssetsandGoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019f193b-e72a-7d3d-a4ea-a7ac6503c5aa" 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_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019f193b-e72a-7d3d-a4ea-a7ac6503c5aa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f193b-e72a-758f-b538-2c6cf4b7c843" 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_us-gaap_ScheduleOfGoodwillTable_019f193b-e72a-7d3d-a4ea-a7ac6503c5aa" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f193b-e72a-758f-b538-2c6cf4b7c843" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-758f-b538-2c6cf4b7c843_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_019f193b-e72a-758f-b538-2c6cf4b7c843" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-758f-b538-2c6cf4b7c843_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-784e-9efa-bfbd1f3fd4be" 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_019f193b-e72a-758f-b538-2c6cf4b7c843" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-784e-9efa-bfbd1f3fd4be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019f193b-e72a-73c2-a813-6089d92e09f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-784e-9efa-bfbd1f3fd4be" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019f193b-e72a-73c2-a813-6089d92e09f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PatentsMember_019f193b-e72a-7999-836f-e7698b0cb90d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PatentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-784e-9efa-bfbd1f3fd4be" xlink:to="loc_us-gaap_PatentsMember_019f193b-e72a-7999-836f-e7698b0cb90d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019f193b-e72a-7958-aaef-7585aa9d510b" 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_019f193b-e72a-784e-9efa-bfbd1f3fd4be" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019f193b-e72a-7958-aaef-7585aa9d510b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019f193b-e72a-7726-8c67-263376558b54" 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_ScheduleOfGoodwillTable_019f193b-e72a-7d3d-a4ea-a7ac6503c5aa" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019f193b-e72a-7726-8c67-263376558b54" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-7726-8c67-263376558b54_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_019f193b-e72a-7726-8c67-263376558b54" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-7726-8c67-263376558b54_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-79fd-981f-d1fc8bfba7a6" 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_019f193b-e72a-7726-8c67-263376558b54" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-79fd-981f-d1fc8bfba7a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InProcessResearchAndDevelopmentMember_019f193b-e72a-7178-815e-866dab32121f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InProcessResearchAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019f193b-e72a-79fd-981f-d1fc8bfba7a6" xlink:to="loc_us-gaap_InProcessResearchAndDevelopmentMember_019f193b-e72a-7178-815e-866dab32121f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72a-7f5b-94c9-01076be836c5" 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_019f193b-e72a-7d3d-a4ea-a7ac6503c5aa" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72a-7f5b-94c9-01076be836c5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72a-7f5b-94c9-01076be836c5_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_019f193b-e72a-7f5b-94c9-01076be836c5" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72a-7f5b-94c9-01076be836c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72a-76a7-a0fa-82e9bdf06eb4" 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_019f193b-e72a-7f5b-94c9-01076be836c5" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72a-76a7-a0fa-82e9bdf06eb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_MedsurgMember_019f193b-e72a-79f7-bf77-e635aebb3189" xlink:href="bsx-20260630.xsd#bsx_MedsurgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72a-76a7-a0fa-82e9bdf06eb4" xlink:to="loc_bsx_MedsurgMember_019f193b-e72a-79f7-bf77-e635aebb3189" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CardiovascularMember_019f193b-e72a-75c8-9ffd-653f828dc5a7" xlink:href="bsx-20260630.xsd#bsx_CardiovascularMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72a-76a7-a0fa-82e9bdf06eb4" xlink:to="loc_bsx_CardiovascularMember_019f193b-e72a-75c8-9ffd-653f828dc5a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019f193b-e72a-737d-8463-af51dc1e8adf" 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_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019f193b-e72a-737d-8463-af51dc1e8adf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019f193b-e72a-7861-8a7c-8f9eab5ce603" 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_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019f193b-e72a-7861-8a7c-8f9eab5ce603" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillGross_019f193b-e72a-720d-8f9b-b1eb7e34281c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:to="loc_us-gaap_GoodwillGross_019f193b-e72a-720d-8f9b-b1eb7e34281c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019f193b-e72a-7b7b-b770-1e230df106f1" 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_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019f193b-e72a-7b7b-b770-1e230df106f1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019f193b-e72a-77d1-9a2a-8bd7938878f6" 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_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_019f193b-e72a-77d1-9a2a-8bd7938878f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_019f193b-e72a-76f1-976c-326740b23e39" 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_bsx_IntangibleAssetsandGoodwillLineItems_019f193b-e72a-750e-9810-37aa7a62eee3" xlink:to="loc_us-gaap_GoodwillRollForward_019f193b-e72a-76f1-976c-326740b23e39" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f193b-e72a-7a89-8845-be99e6730607" 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_019f193b-e72a-76f1-976c-326740b23e39" xlink:to="loc_us-gaap_Goodwill_019f193b-e72a-7a89-8845-be99e6730607" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_019f193b-e72a-7b31-917e-54ee51cb8440" 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_019f193b-e72a-76f1-976c-326740b23e39" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_019f193b-e72a-7b31-917e-54ee51cb8440" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019f193b-e72a-7a79-b675-f6d4e983f55b" 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_019f193b-e72a-76f1-976c-326740b23e39" xlink:to="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_019f193b-e72a-7a79-b675-f6d4e983f55b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f193b-e72a-7b67-bca9-e63e23917cac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsNarrativeDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" 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_019f193b-e72a-7181-874c-2d3dbd1b9f7c" 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_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_us-gaap_DerivativeTable_019f193b-e72a-7181-874c-2d3dbd1b9f7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7270-bda7-c847d6329dd9" 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_DerivativeTable_019f193b-e72a-7181-874c-2d3dbd1b9f7c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7270-bda7-c847d6329dd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7270-bda7-c847d6329dd9_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_019f193b-e72a-7270-bda7-c847d6329dd9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7270-bda7-c847d6329dd9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7edd-8a3d-459d2404d402" 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_019f193b-e72a-7270-bda7-c847d6329dd9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7edd-8a3d-459d2404d402" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_December2027NotesMember_019f193b-e72a-7719-a55c-5da37351fac7" xlink:href="bsx-20260630.xsd#bsx_December2027NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7edd-8a3d-459d2404d402" xlink:to="loc_bsx_December2027NotesMember_019f193b-e72a-7719-a55c-5da37351fac7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-7ca2-b046-80f2ce3f9548" 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_019f193b-e72a-7181-874c-2d3dbd1b9f7c" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-7ca2-b046-80f2ce3f9548" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7ca2-b046-80f2ce3f9548_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_019f193b-e72a-7ca2-b046-80f2ce3f9548" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7ca2-b046-80f2ce3f9548_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7e88-9f9d-b80e3eb5f121" 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_019f193b-e72a-7ca2-b046-80f2ce3f9548" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7e88-9f9d-b80e3eb5f121" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7bbc-9e9a-d4826a914fdd" 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_019f193b-e72a-7e88-9f9d-b80e3eb5f121" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7bbc-9e9a-d4826a914fdd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_019f193b-e72a-72c4-82e0-e76c928f8056" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7e88-9f9d-b80e3eb5f121" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_019f193b-e72a-72c4-82e0-e76c928f8056" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7904-b2ad-2ac3e09c74d0" 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_019f193b-e72a-7181-874c-2d3dbd1b9f7c" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7904-b2ad-2ac3e09c74d0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7904-b2ad-2ac3e09c74d0_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_019f193b-e72a-7904-b2ad-2ac3e09c74d0" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7904-b2ad-2ac3e09c74d0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7845-8974-94a74fee0437" 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_019f193b-e72a-7904-b2ad-2ac3e09c74d0" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7845-8974-94a74fee0437" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7f30-a2a5-dcf26ee464d7" 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_019f193b-e72a-7845-8974-94a74fee0437" xlink:to="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7f30-a2a5-dcf26ee464d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-735b-b3cd-fef337f8f598" 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_019f193b-e72a-7845-8974-94a74fee0437" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-735b-b3cd-fef337f8f598" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-73a7-b062-3ad7c1dc8a9c" 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_019f193b-e72a-7181-874c-2d3dbd1b9f7c" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-73a7-b062-3ad7c1dc8a9c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-73a7-b062-3ad7c1dc8a9c_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_019f193b-e72a-73a7-b062-3ad7c1dc8a9c" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-73a7-b062-3ad7c1dc8a9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7236-a61f-6655e4ac7f08" 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_019f193b-e72a-73a7-b062-3ad7c1dc8a9c" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7236-a61f-6655e4ac7f08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-753f-9c7c-e3dfa18a6807" 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_019f193b-e72a-7236-a61f-6655e4ac7f08" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-753f-9c7c-e3dfa18a6807" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019f193b-e72a-7c54-9337-d81d6167a5be" 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_019f193b-e72a-7236-a61f-6655e4ac7f08" xlink:to="loc_us-gaap_NondesignatedMember_019f193b-e72a-7c54-9337-d81d6167a5be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f193b-e72a-797f-84e5-3cd47493d0d2" 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_019f193b-e72a-7181-874c-2d3dbd1b9f7c" xlink:to="loc_srt_RangeAxis_019f193b-e72a-797f-84e5-3cd47493d0d2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f193b-e72a-797f-84e5-3cd47493d0d2_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_019f193b-e72a-797f-84e5-3cd47493d0d2" xlink:to="loc_srt_RangeMember_019f193b-e72a-797f-84e5-3cd47493d0d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f193b-e72a-7ec6-a310-8b0cdce311a8" 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_019f193b-e72a-797f-84e5-3cd47493d0d2" xlink:to="loc_srt_RangeMember_019f193b-e72a-7ec6-a310-8b0cdce311a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f193b-e72a-726e-92d9-fc46d20c2dbb" 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_019f193b-e72a-7ec6-a310-8b0cdce311a8" xlink:to="loc_srt_MinimumMember_019f193b-e72a-726e-92d9-fc46d20c2dbb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f193b-e72a-75f8-b826-e3db8ba1f412" 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_019f193b-e72a-7ec6-a310-8b0cdce311a8" xlink:to="loc_srt_MaximumMember_019f193b-e72a-75f8-b826-e3db8ba1f412" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f193b-e72a-7107-b3c7-953e4214fc67" 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_DerivativeTable_019f193b-e72a-7181-874c-2d3dbd1b9f7c" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f193b-e72a-7107-b3c7-953e4214fc67" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7107-b3c7-953e4214fc67_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_019f193b-e72a-7107-b3c7-953e4214fc67" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7107-b3c7-953e4214fc67_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7bd2-a94a-190516a2f7b6" 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_019f193b-e72a-7107-b3c7-953e4214fc67" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7bd2-a94a-190516a2f7b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019f193b-e72a-7fe7-b29e-9454151e3d3d" 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_019f193b-e72a-7bd2-a94a-190516a2f7b6" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019f193b-e72a-7fe7-b29e-9454151e3d3d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f193b-e72a-7f43-8192-e6280bb8e403" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_us-gaap_LongTermDebt_019f193b-e72a-7f43-8192-e6280bb8e403" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f193b-e72a-7a36-812b-ce94246f57c0" 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_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f193b-e72a-7a36-812b-ce94246f57c0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ForwardCurrencyContractsTimeToMaturity_019f193b-e72a-78a1-b47e-4ef84a233453" xlink:href="bsx-20260630.xsd#bsx_ForwardCurrencyContractsTimeToMaturity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_bsx_ForwardCurrencyContractsTimeToMaturity_019f193b-e72a-78a1-b47e-4ef84a233453" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeRemainingMaturity1_019f193b-e72a-7791-ad42-77a9fc8d740c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeRemainingMaturity1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_us-gaap_DerivativeRemainingMaturity1_019f193b-e72a-7791-ad42-77a9fc8d740c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsAtCarryingValue_019f193b-e72a-79c1-ad41-f2bd71fccf19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MoneyMarketFundsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_us-gaap_MoneyMarketFundsAtCarryingValue_019f193b-e72a-79c1-ad41-f2bd71fccf19" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Cash_019f193b-e72a-76f0-8868-80ebba5df73e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Cash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_us-gaap_Cash_019f193b-e72a-76f0-8868-80ebba5df73e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019f193b-e72a-7def-b823-585a82f79715" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7de5-9fbd-89ed49e90e20" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019f193b-e72a-7def-b823-585a82f79715" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsNotionalAmountsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsNotionalAmountsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsNotionalAmountsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7783-9eb7-4117616d686a" 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_019f193b-e72a-7590-be54-3cc6cc2fe38c" 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_019f193b-e72a-7783-9eb7-4117616d686a" xlink:to="loc_us-gaap_DerivativeTable_019f193b-e72a-7590-be54-3cc6cc2fe38c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-791b-bdc0-7182f5f4f307" 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_019f193b-e72a-7590-be54-3cc6cc2fe38c" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-791b-bdc0-7182f5f4f307" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-791b-bdc0-7182f5f4f307_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_019f193b-e72a-791b-bdc0-7182f5f4f307" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-791b-bdc0-7182f5f4f307_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7d55-a33c-f6c409f10fbf" 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_019f193b-e72a-791b-bdc0-7182f5f4f307" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7d55-a33c-f6c409f10fbf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7bc8-a461-2e41bb94139d" 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_019f193b-e72a-7d55-a33c-f6c409f10fbf" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7bc8-a461-2e41bb94139d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ForeigncurrencydenominatedindebtMember_019f193b-e72a-75c0-a145-eb6b0a566164" xlink:href="bsx-20260630.xsd#bsx_ForeigncurrencydenominatedindebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7d55-a33c-f6c409f10fbf" xlink:to="loc_bsx_ForeigncurrencydenominatedindebtMember_019f193b-e72a-75c0-a145-eb6b0a566164" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7c30-b2d7-32f6a3685403" 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_019f193b-e72a-7590-be54-3cc6cc2fe38c" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7c30-b2d7-32f6a3685403" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7c30-b2d7-32f6a3685403_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_019f193b-e72a-7c30-b2d7-32f6a3685403" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7c30-b2d7-32f6a3685403_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7995-8899-6e9fceaa8782" 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_019f193b-e72a-7c30-b2d7-32f6a3685403" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7995-8899-6e9fceaa8782" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7554-9d39-d7f62ee662a2" 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_019f193b-e72a-7995-8899-6e9fceaa8782" xlink:to="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7554-9d39-d7f62ee662a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7828-b014-b12145673bee" 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_019f193b-e72a-7995-8899-6e9fceaa8782" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7828-b014-b12145673bee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7e78-ae11-7e47c5f04a12" 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_019f193b-e72a-7590-be54-3cc6cc2fe38c" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7e78-ae11-7e47c5f04a12" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7e78-ae11-7e47c5f04a12_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_019f193b-e72a-7e78-ae11-7e47c5f04a12" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7e78-ae11-7e47c5f04a12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-75eb-be98-1b59fb0f6a22" 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_019f193b-e72a-7e78-ae11-7e47c5f04a12" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-75eb-be98-1b59fb0f6a22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-793a-bc62-cd597827c497" 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_019f193b-e72a-75eb-be98-1b59fb0f6a22" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-793a-bc62-cd597827c497" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019f193b-e72a-73d7-a95c-b5ff5d656168" 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_019f193b-e72a-75eb-be98-1b59fb0f6a22" xlink:to="loc_us-gaap_NondesignatedMember_019f193b-e72a-73d7-a95c-b5ff5d656168" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7fe8-949c-c6de8edcb19f" 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_DerivativeTable_019f193b-e72a-7590-be54-3cc6cc2fe38c" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7fe8-949c-c6de8edcb19f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7fe8-949c-c6de8edcb19f_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_019f193b-e72a-7fe8-949c-c6de8edcb19f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7fe8-949c-c6de8edcb19f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7ef6-aec8-2e6f880c2ad0" 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_019f193b-e72a-7fe8-949c-c6de8edcb19f" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7ef6-aec8-2e6f880c2ad0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_December2027NotesMember_019f193b-e72a-70b2-9af2-c029479ccd49" xlink:href="bsx-20260630.xsd#bsx_December2027NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7ef6-aec8-2e6f880c2ad0" xlink:to="loc_bsx_December2027NotesMember_019f193b-e72a-70b2-9af2-c029479ccd49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019f193b-e72a-7c86-b8d6-c9ab228f6158" 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_019f193b-e72a-7783-9eb7-4117616d686a" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019f193b-e72a-7c86-b8d6-c9ab228f6158" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f193b-e72a-7f34-99b4-d3c8ce29e01e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019f193b-e72a-7783-9eb7-4117616d686a" xlink:to="loc_us-gaap_LongTermDebt_019f193b-e72a-7f34-99b4-d3c8ce29e01e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsEffectofHedgingRelationshipsonAccumulatedOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsEffectofHedgingRelationshipsonAccumulatedOtherComprehensiveIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsEffectofHedgingRelationshipsonAccumulatedOtherComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-74b9-8e29-fc799094b304" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-74b9-8e29-fc799094b304" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-74b9-8e29-fc799094b304_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_019f193b-e72a-74b9-8e29-fc799094b304" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-74b9-8e29-fc799094b304_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-76ad-aa9b-901d4d069deb" 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_019f193b-e72a-74b9-8e29-fc799094b304" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-76ad-aa9b-901d4d069deb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b15-9ed3-931af53d2ffc" 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_019f193b-e72a-76ad-aa9b-901d4d069deb" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b15-9ed3-931af53d2ffc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ForeigncurrencydenominatedindebtMember_019f193b-e72a-7a35-9fae-5d609c16e56a" xlink:href="bsx-20260630.xsd#bsx_ForeigncurrencydenominatedindebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-76ad-aa9b-901d4d069deb" xlink:to="loc_bsx_ForeigncurrencydenominatedindebtMember_019f193b-e72a-7a35-9fae-5d609c16e56a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-769a-a19e-3fd2e2127d38" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-769a-a19e-3fd2e2127d38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-769a-a19e-3fd2e2127d38_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_019f193b-e72a-769a-a19e-3fd2e2127d38" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-769a-a19e-3fd2e2127d38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-721f-a10c-5ee4bc69ad25" 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_019f193b-e72a-769a-a19e-3fd2e2127d38" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-721f-a10c-5ee4bc69ad25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-701c-b411-339a8df74ed2" 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_019f193b-e72a-721f-a10c-5ee4bc69ad25" xlink:to="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-701c-b411-339a8df74ed2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7c4a-b382-5aae0d4bdc44" 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_019f193b-e72a-721f-a10c-5ee4bc69ad25" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7c4a-b382-5aae0d4bdc44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7461-8478-78b5f7e70f0c" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7461-8478-78b5f7e70f0c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7461-8478-78b5f7e70f0c_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_019f193b-e72a-7461-8478-78b5f7e70f0c" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7461-8478-78b5f7e70f0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7a8e-bbc1-3391f4ea1910" 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_019f193b-e72a-7461-8478-78b5f7e70f0c" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7a8e-bbc1-3391f4ea1910" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-7534-8c9b-39854fd5f556" 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_019f193b-e72a-7a8e-bbc1-3391f4ea1910" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-7534-8c9b-39854fd5f556" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f193b-e72a-75e7-8b98-63b4c73ba4c0" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f193b-e72a-75e7-8b98-63b4c73ba4c0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72a-7667-ae82-5f8a84bd06a7" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72a-7667-ae82-5f8a84bd06a7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7667-ae82-5f8a84bd06a7_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_019f193b-e72a-7667-ae82-5f8a84bd06a7" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7667-ae82-5f8a84bd06a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72a-71a6-addf-2a223cc291c9" 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_019f193b-e72a-7667-ae82-5f8a84bd06a7" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72a-71a6-addf-2a223cc291c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f193b-e72a-7f6e-9345-5e94459bd79a" 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_019f193b-e72a-71a6-addf-2a223cc291c9" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f193b-e72a-7f6e-9345-5e94459bd79a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-741f-9b69-382abdc1dd56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-741f-9b69-382abdc1dd56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax_019f193b-e72a-7160-a937-5771b12e5973" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax_019f193b-e72a-7160-a937-5771b12e5973" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019f193b-e72a-70ae-96f3-646249f8f2f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019f193b-e72a-70ae-96f3-646249f8f2f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-7ad3-9fc0-6b3245ee50b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-7ad3-9fc0-6b3245ee50b0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax_019f193b-e72a-7d0e-957c-9475520fc636" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax_019f193b-e72a-7d0e-957c-9475520fc636" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_019f193b-e72a-702c-b3da-d2b0eb2a0048" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_019f193b-e72a-702c-b3da-d2b0eb2a0048" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-7cf9-a4e7-8d1cdbc80fc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-7cf9-a4e7-8d1cdbc80fc9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax_019f193b-e72a-7426-914d-fb71e62efa3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax_019f193b-e72a-7426-914d-fb71e62efa3b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax_019f193b-e72a-7e58-a0f5-707f80cf9033" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax_019f193b-e72a-7e58-a0f5-707f80cf9033" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsBeforeTax_019f193b-e72a-71b4-897f-e5c897c0bf34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsBeforeTax_019f193b-e72a-71b4-897f-e5c897c0bf34" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsTax_019f193b-e72a-738c-86bb-60d795d8b62b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsTax_019f193b-e72a-738c-86bb-60d795d8b62b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsAfterTax_019f193b-e72a-7a62-9240-081c2417b1ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsAfterTax_019f193b-e72a-7a62-9240-081c2417b1ef" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019f193b-e72a-74db-896d-dfa50329bade" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019f193b-e72a-74db-896d-dfa50329bade" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsEffectofHedgingRelationshipsonAccumulatedOtherComprehensiveIncomeDetails_1" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsEffectofHedgingRelationshipsonAccumulatedOtherComprehensiveIncomeDetails_1"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsEffectofHedgingRelationshipsonAccumulatedOtherComprehensiveIncomeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-74b9-8e29-fc799094b304" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-74b9-8e29-fc799094b304" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-74b9-8e29-fc799094b304_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_019f193b-e72a-74b9-8e29-fc799094b304" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-74b9-8e29-fc799094b304_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-76ad-aa9b-901d4d069deb" 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_019f193b-e72a-74b9-8e29-fc799094b304" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-76ad-aa9b-901d4d069deb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b15-9ed3-931af53d2ffc" 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_019f193b-e72a-76ad-aa9b-901d4d069deb" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b15-9ed3-931af53d2ffc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ForeigncurrencydenominatedindebtMember_019f193b-e72a-7a35-9fae-5d609c16e56a" xlink:href="bsx-20260630.xsd#bsx_ForeigncurrencydenominatedindebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-76ad-aa9b-901d4d069deb" xlink:to="loc_bsx_ForeigncurrencydenominatedindebtMember_019f193b-e72a-7a35-9fae-5d609c16e56a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-769a-a19e-3fd2e2127d38" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-769a-a19e-3fd2e2127d38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-769a-a19e-3fd2e2127d38_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_019f193b-e72a-769a-a19e-3fd2e2127d38" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-769a-a19e-3fd2e2127d38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-721f-a10c-5ee4bc69ad25" 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_019f193b-e72a-769a-a19e-3fd2e2127d38" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-721f-a10c-5ee4bc69ad25" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-701c-b411-339a8df74ed2" 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_019f193b-e72a-721f-a10c-5ee4bc69ad25" xlink:to="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-701c-b411-339a8df74ed2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7c4a-b382-5aae0d4bdc44" 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_019f193b-e72a-721f-a10c-5ee4bc69ad25" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7c4a-b382-5aae0d4bdc44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7461-8478-78b5f7e70f0c" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7461-8478-78b5f7e70f0c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7461-8478-78b5f7e70f0c_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_019f193b-e72a-7461-8478-78b5f7e70f0c" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7461-8478-78b5f7e70f0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7a8e-bbc1-3391f4ea1910" 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_019f193b-e72a-7461-8478-78b5f7e70f0c" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7a8e-bbc1-3391f4ea1910" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-7534-8c9b-39854fd5f556" 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_019f193b-e72a-7a8e-bbc1-3391f4ea1910" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-7534-8c9b-39854fd5f556" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72a-7667-ae82-5f8a84bd06a7" 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_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_019f193b-e72a-7f61-aaf1-c682a8383aa6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72a-7667-ae82-5f8a84bd06a7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7667-ae82-5f8a84bd06a7_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_019f193b-e72a-7667-ae82-5f8a84bd06a7" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72a-7667-ae82-5f8a84bd06a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72a-71a6-addf-2a223cc291c9" 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_019f193b-e72a-7667-ae82-5f8a84bd06a7" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72a-71a6-addf-2a223cc291c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f193b-e72a-7f6e-9345-5e94459bd79a" 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_019f193b-e72a-71a6-addf-2a223cc291c9" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f193b-e72a-7f6e-9345-5e94459bd79a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-741f-9b69-382abdc1dd56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-741f-9b69-382abdc1dd56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax_019f193b-e72a-7160-a937-5771b12e5973" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax_019f193b-e72a-7160-a937-5771b12e5973" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019f193b-e72a-70ae-96f3-646249f8f2f0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_019f193b-e72a-70ae-96f3-646249f8f2f0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-7ad3-9fc0-6b3245ee50b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-7ad3-9fc0-6b3245ee50b0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax_019f193b-e72a-7d0e-957c-9475520fc636" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax_019f193b-e72a-7d0e-957c-9475520fc636" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_019f193b-e72a-702c-b3da-d2b0eb2a0048" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_019f193b-e72a-702c-b3da-d2b0eb2a0048" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-7cf9-a4e7-8d1cdbc80fc9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax_019f193b-e72a-7cf9-a4e7-8d1cdbc80fc9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax_019f193b-e72a-7426-914d-fb71e62efa3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsTax_019f193b-e72a-7426-914d-fb71e62efa3b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax_019f193b-e72a-7e58-a0f5-707f80cf9033" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseBeforeAdjustmentsAfterTax_019f193b-e72a-7e58-a0f5-707f80cf9033" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsBeforeTax_019f193b-e72a-71b4-897f-e5c897c0bf34" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsBeforeTax_019f193b-e72a-71b4-897f-e5c897c0bf34" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsTax_019f193b-e72a-738c-86bb-60d795d8b62b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsTax_019f193b-e72a-738c-86bb-60d795d8b62b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsAfterTax_019f193b-e72a-7a62-9240-081c2417b1ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossDerivativeExcludedComponentIncreaseDecreaseAdjustmentsAfterTax_019f193b-e72a-7a62-9240-081c2417b1ef" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019f193b-e72a-74db-896d-dfa50329bade" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_019f193b-e72a-7a75-86b9-4b9f23383325" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019f193b-e72a-74db-896d-dfa50329bade" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsAmountofPreTaxGainLossthatmaybeReclassifiedtoEarningsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsAmountofPreTaxGainLossthatmaybeReclassifiedtoEarningsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsAmountofPreTaxGainLossthatmaybeReclassifiedtoEarningsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7f3f-8f06-fc6077d44ed7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7f3f-8f06-fc6077d44ed7" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-730d-ac69-e99759109266" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-730d-ac69-e99759109266" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-730d-ac69-e99759109266_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_019f193b-e72a-730d-ac69-e99759109266" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-730d-ac69-e99759109266_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7874-b31d-4c33f734e7ba" 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_019f193b-e72a-730d-ac69-e99759109266" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7874-b31d-4c33f734e7ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b43-90f2-1bdd927f3002" 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_019f193b-e72a-7874-b31d-4c33f734e7ba" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b43-90f2-1bdd927f3002" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7be3-ba74-d8679f3e7629" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7be3-ba74-d8679f3e7629" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7be3-ba74-d8679f3e7629_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_019f193b-e72a-7be3-ba74-d8679f3e7629" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7be3-ba74-d8679f3e7629_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-72f2-a267-149906aa7a57" 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_019f193b-e72a-7be3-ba74-d8679f3e7629" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-72f2-a267-149906aa7a57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7c0e-be01-329ec74b747e" 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_019f193b-e72a-72f2-a267-149906aa7a57" xlink:to="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7c0e-be01-329ec74b747e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7894-9dfe-db1530256fe8" 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_019f193b-e72a-72f2-a267-149906aa7a57" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7894-9dfe-db1530256fe8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f193b-e72a-752c-bf67-cb5acf9587ef" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f193b-e72a-752c-bf67-cb5acf9587ef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-71e9-906b-5bf02f83a600" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7f3f-8f06-fc6077d44ed7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-71e9-906b-5bf02f83a600" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsAmountofPreTaxGainLossthatmaybeReclassifiedtoEarningsDetails_1" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsAmountofPreTaxGainLossthatmaybeReclassifiedtoEarningsDetails_1"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsAmountofPreTaxGainLossthatmaybeReclassifiedtoEarningsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7f3f-8f06-fc6077d44ed7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7f3f-8f06-fc6077d44ed7" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-730d-ac69-e99759109266" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-730d-ac69-e99759109266" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-730d-ac69-e99759109266_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_019f193b-e72a-730d-ac69-e99759109266" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-730d-ac69-e99759109266_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7874-b31d-4c33f734e7ba" 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_019f193b-e72a-730d-ac69-e99759109266" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-7874-b31d-4c33f734e7ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b43-90f2-1bdd927f3002" 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_019f193b-e72a-7874-b31d-4c33f734e7ba" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b43-90f2-1bdd927f3002" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7be3-ba74-d8679f3e7629" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-773b-b784-beb3f22b66b0" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019f193b-e72a-7be3-ba74-d8679f3e7629" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7be3-ba74-d8679f3e7629_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_019f193b-e72a-7be3-ba74-d8679f3e7629" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-7be3-ba74-d8679f3e7629_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-72f2-a267-149906aa7a57" 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_019f193b-e72a-7be3-ba74-d8679f3e7629" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019f193b-e72a-72f2-a267-149906aa7a57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7c0e-be01-329ec74b747e" 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_019f193b-e72a-72f2-a267-149906aa7a57" xlink:to="loc_us-gaap_CashFlowHedgingMember_019f193b-e72a-7c0e-be01-329ec74b747e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7894-9dfe-db1530256fe8" 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_019f193b-e72a-72f2-a267-149906aa7a57" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019f193b-e72a-7894-9dfe-db1530256fe8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-71e9-906b-5bf02f83a600" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7f3f-8f06-fc6077d44ed7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019f193b-e72a-71e9-906b-5bf02f83a600" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsLocationonUnauditedConsolidatedStatementsofOperationsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsLocationonUnauditedConsolidatedStatementsofOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsLocationonUnauditedConsolidatedStatementsofOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-75ca-968b-5e8006c6b9de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-75ca-968b-5e8006c6b9de" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-75f0-93a9-97483be63f0a" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-75ca-968b-5e8006c6b9de" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-75f0-93a9-97483be63f0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-75f0-93a9-97483be63f0a_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_019f193b-e72a-75f0-93a9-97483be63f0a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-75f0-93a9-97483be63f0a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-70fb-840b-e7289a244bef" 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_019f193b-e72a-75f0-93a9-97483be63f0a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-70fb-840b-e7289a244bef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019f193b-e72a-7822-8eab-f50127f28b18" 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_019f193b-e72a-70fb-840b-e7289a244bef" xlink:to="loc_us-gaap_NondesignatedMember_019f193b-e72a-7822-8eab-f50127f28b18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f193b-e72a-74dc-980c-c2dd5ddcc143" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-75ca-968b-5e8006c6b9de" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_019f193b-e72a-74dc-980c-c2dd5ddcc143" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_019f193b-e72a-7cd6-bb8c-cd0122ba6b82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_019f193b-e72a-7cd6-bb8c-cd0122ba6b82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019f193b-e72a-72cf-a6d0-37216f84ca04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019f193b-e72a-72cf-a6d0-37216f84ca04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Netcurrencyexchangegainloss_019f193b-e72a-7ee4-b210-ff18e762020c" xlink:href="bsx-20260630.xsd#bsx_Netcurrencyexchangegainloss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_bsx_Netcurrencyexchangegainloss_019f193b-e72a-7ee4-b210-ff18e762020c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsLocationonUnauditedConsolidatedStatementsofOperationsDetails_1" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsLocationonUnauditedConsolidatedStatementsofOperationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsLocationonUnauditedConsolidatedStatementsofOperationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-75ca-968b-5e8006c6b9de" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-75ca-968b-5e8006c6b9de" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-75f0-93a9-97483be63f0a" 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_019f193b-e72a-75ca-968b-5e8006c6b9de" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-75f0-93a9-97483be63f0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-75f0-93a9-97483be63f0a_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_019f193b-e72a-75f0-93a9-97483be63f0a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-75f0-93a9-97483be63f0a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-70fb-840b-e7289a244bef" 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_019f193b-e72a-75f0-93a9-97483be63f0a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-70fb-840b-e7289a244bef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019f193b-e72a-7822-8eab-f50127f28b18" 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_019f193b-e72a-70fb-840b-e7289a244bef" xlink:to="loc_us-gaap_NondesignatedMember_019f193b-e72a-7822-8eab-f50127f28b18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_019f193b-e72a-7cd6-bb8c-cd0122ba6b82" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments_019f193b-e72a-7cd6-bb8c-cd0122ba6b82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019f193b-e72a-72cf-a6d0-37216f84ca04" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019f193b-e72a-72cf-a6d0-37216f84ca04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Netcurrencyexchangegainloss_019f193b-e72a-7ee4-b210-ff18e762020c" xlink:href="bsx-20260630.xsd#bsx_Netcurrencyexchangegainloss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_019f193b-e72a-7378-8518-68628686ed21" xlink:to="loc_bsx_Netcurrencyexchangegainloss_019f193b-e72a-7ee4-b210-ff18e762020c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsBalanceSheetLocationDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsBalanceSheetLocationDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsBalanceSheetLocationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" 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_019f193b-e72a-7500-ad79-80e8714a04a6" 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_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f193b-e72a-7ca5-9d92-34206a24e3f0" 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_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:to="loc_us-gaap_StatementOfFinancialPositionLocationBalanceAxis_019f193b-e72a-7ca5-9d92-34206a24e3f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-786b-a628-2c94ec43aa94" 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_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-786b-a628-2c94ec43aa94" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-786b-a628-2c94ec43aa94_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_019f193b-e72a-786b-a628-2c94ec43aa94" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-786b-a628-2c94ec43aa94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-77b6-ab24-338ac00c881f" 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_019f193b-e72a-786b-a628-2c94ec43aa94" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-77b6-ab24-338ac00c881f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b1e-8fb4-9227471c6003" 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_019f193b-e72a-77b6-ab24-338ac00c881f" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b1e-8fb4-9227471c6003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7e51-b4a5-fab724bc416a" 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_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7e51-b4a5-fab724bc416a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7e51-b4a5-fab724bc416a_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_019f193b-e72a-7e51-b4a5-fab724bc416a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7e51-b4a5-fab724bc416a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7bb2-8afa-72cefbcf83bd" 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_019f193b-e72a-7e51-b4a5-fab724bc416a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7bb2-8afa-72cefbcf83bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-743b-842f-20b00ebec221" 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_019f193b-e72a-7bb2-8afa-72cefbcf83bd" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-743b-842f-20b00ebec221" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019f193b-e72a-765c-8a29-b9a3906df0b2" 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_019f193b-e72a-7bb2-8afa-72cefbcf83bd" xlink:to="loc_us-gaap_NondesignatedMember_019f193b-e72a-765c-8a29-b9a3906df0b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7120-a28e-937e332126e9" 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_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7120-a28e-937e332126e9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7120-a28e-937e332126e9_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_019f193b-e72a-7120-a28e-937e332126e9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7120-a28e-937e332126e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7168-980b-7028a131cc66" 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_019f193b-e72a-7120-a28e-937e332126e9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7168-980b-7028a131cc66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_December2027NotesMember_019f193b-e72a-7778-bea5-f349ab067e1a" xlink:href="bsx-20260630.xsd#bsx_December2027NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7168-980b-7028a131cc66" xlink:to="loc_bsx_December2027NotesMember_019f193b-e72a-7778-bea5-f349ab067e1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_019f193b-e72a-704b-b801-bbc9444b40b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_019f193b-e72a-704b-b801-bbc9444b40b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_019f193b-e72a-7e06-9614-f689120f2682" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_019f193b-e72a-7e06-9614-f689120f2682" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019f193b-e72a-7d1b-8f5c-9c54c3f8b90e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019f193b-e72a-7d1b-8f5c-9c54c3f8b90e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_019f193b-e72a-75e7-b837-1e08b24696e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_019f193b-e72a-75e7-b837-1e08b24696e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_019f193b-e72a-78f6-8ebd-985684b05ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_019f193b-e72a-78f6-8ebd-985684b05ebb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019f193b-e72a-728d-bda8-f7fcab1e34c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019f193b-e72a-728d-bda8-f7fcab1e34c4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f193b-e72a-7e54-82e4-59794232310f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_LongTermDebt_019f193b-e72a-7e54-82e4-59794232310f" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsBalanceSheetLocationDetails_1" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsBalanceSheetLocationDetails_1"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsBalanceSheetLocationDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" 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_019f193b-e72a-7500-ad79-80e8714a04a6" 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_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-786b-a628-2c94ec43aa94" 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_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019f193b-e72a-786b-a628-2c94ec43aa94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-786b-a628-2c94ec43aa94_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_019f193b-e72a-786b-a628-2c94ec43aa94" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-786b-a628-2c94ec43aa94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-77b6-ab24-338ac00c881f" 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_019f193b-e72a-786b-a628-2c94ec43aa94" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019f193b-e72a-77b6-ab24-338ac00c881f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b1e-8fb4-9227471c6003" 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_019f193b-e72a-77b6-ab24-338ac00c881f" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019f193b-e72a-7b1e-8fb4-9227471c6003" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7e51-b4a5-fab724bc416a" 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_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:to="loc_us-gaap_HedgingDesignationAxis_019f193b-e72a-7e51-b4a5-fab724bc416a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7e51-b4a5-fab724bc416a_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_019f193b-e72a-7e51-b4a5-fab724bc416a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7e51-b4a5-fab724bc416a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7bb2-8afa-72cefbcf83bd" 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_019f193b-e72a-7e51-b4a5-fab724bc416a" xlink:to="loc_us-gaap_HedgingDesignationDomain_019f193b-e72a-7bb2-8afa-72cefbcf83bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-743b-842f-20b00ebec221" 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_019f193b-e72a-7bb2-8afa-72cefbcf83bd" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019f193b-e72a-743b-842f-20b00ebec221" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019f193b-e72a-765c-8a29-b9a3906df0b2" 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_019f193b-e72a-7bb2-8afa-72cefbcf83bd" xlink:to="loc_us-gaap_NondesignatedMember_019f193b-e72a-765c-8a29-b9a3906df0b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7120-a28e-937e332126e9" 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_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_019f193b-e72a-7500-ad79-80e8714a04a6" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72a-7120-a28e-937e332126e9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7120-a28e-937e332126e9_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_019f193b-e72a-7120-a28e-937e332126e9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7120-a28e-937e332126e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7168-980b-7028a131cc66" 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_019f193b-e72a-7120-a28e-937e332126e9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7168-980b-7028a131cc66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_December2027NotesMember_019f193b-e72a-7778-bea5-f349ab067e1a" xlink:href="bsx-20260630.xsd#bsx_December2027NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72a-7168-980b-7028a131cc66" xlink:to="loc_bsx_December2027NotesMember_019f193b-e72a-7778-bea5-f349ab067e1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_019f193b-e72a-704b-b801-bbc9444b40b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesAssetsAtFairValue_019f193b-e72a-704b-b801-bbc9444b40b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_019f193b-e72a-7e06-9614-f689120f2682" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsAssetAtFairValue_019f193b-e72a-7e06-9614-f689120f2682" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019f193b-e72a-7d1b-8f5c-9c54c3f8b90e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019f193b-e72a-7d1b-8f5c-9c54c3f8b90e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_019f193b-e72a-75e7-b837-1e08b24696e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_019f193b-e72a-75e7-b837-1e08b24696e2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_019f193b-e72a-78f6-8ebd-985684b05ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue_019f193b-e72a-78f6-8ebd-985684b05ebb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019f193b-e72a-728d-bda8-f7fcab1e34c4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019f193b-e72a-728d-bda8-f7fcab1e34c4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f193b-e72a-7e54-82e4-59794232310f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_019f193b-e72a-720d-ae06-a4f7bf06945f" xlink:to="loc_us-gaap_LongTermDebt_019f193b-e72a-7e54-82e4-59794232310f" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsFairValueDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#HedgingActivitiesandFairValueMeasurementsFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/HedgingActivitiesandFairValueMeasurementsFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" 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_019f193b-e72a-7717-9c4a-3634c04a25e6" 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_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019f193b-e72a-7717-9c4a-3634c04a25e6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f193b-e72a-7178-94e9-c7c234f87a46" 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_019f193b-e72a-7717-9c4a-3634c04a25e6" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f193b-e72a-7178-94e9-c7c234f87a46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7178-94e9-c7c234f87a46_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_019f193b-e72a-7178-94e9-c7c234f87a46" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7178-94e9-c7c234f87a46_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7296-99a9-1244a5c390d5" 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_019f193b-e72a-7178-94e9-c7c234f87a46" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f193b-e72a-7296-99a9-1244a5c390d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019f193b-e72a-7f04-8bee-416f443f0c55" 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_019f193b-e72a-7296-99a9-1244a5c390d5" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019f193b-e72a-7f04-8bee-416f443f0c55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019f193b-e72a-7d6d-9ac6-4eb90287fd3d" 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_019f193b-e72a-7296-99a9-1244a5c390d5" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019f193b-e72a-7d6d-9ac6-4eb90287fd3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019f193b-e72a-727e-b1ee-636387aca85e" 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_019f193b-e72a-7296-99a9-1244a5c390d5" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019f193b-e72a-727e-b1ee-636387aca85e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsAtCarryingValue_019f193b-e72a-71d8-9112-f4656f38b291" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MoneyMarketFundsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_MoneyMarketFundsAtCarryingValue_019f193b-e72a-71d8-9112-f4656f38b291" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNi_019f193b-e72a-75c5-b94e-d7d963c9f6d6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquitySecuritiesFvNi"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_EquitySecuritiesFvNi_019f193b-e72a-75c5-b94e-d7d963c9f6d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_019f193b-e72a-781a-bed2-570d32ebd877" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_DerivativeAssets_019f193b-e72a-781a-bed2-570d32ebd877" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019f193b-e72b-7687-b5fd-9e44220b0471" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019f193b-e72b-7687-b5fd-9e44220b0471" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019f193b-e72b-7fc7-8f71-fe0254c82cc0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_DerivativeLiabilities_019f193b-e72b-7fc7-8f71-fe0254c82cc0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019f193b-e72b-7839-9589-a50b2baf8ea6" 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_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019f193b-e72b-7839-9589-a50b2baf8ea6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_Licensingarrangementsliability_019f193b-e72b-7365-b082-2d4b5d8882bd" xlink:href="bsx-20260630.xsd#bsx_Licensingarrangementsliability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_bsx_Licensingarrangementsliability_019f193b-e72b-7365-b082-2d4b5d8882bd" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_019f193b-e72b-7858-a637-13c1f20cbe99" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019f193b-e72a-7aa1-8e1e-e8e52641c9ce" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_019f193b-e72b-7858-a637-13c1f20cbe99" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsScheduleofDebtDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#ContractualObligationsandCommitmentsScheduleofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7b7b-9e1c-8d954feec679" 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_019f193b-e72b-739f-846e-d83da99429cc" 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_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-739f-846e-d83da99429cc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72b-7447-97f2-3c7fcb2f74e7" 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_019f193b-e72b-739f-846e-d83da99429cc" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72b-7447-97f2-3c7fcb2f74e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7447-97f2-3c7fcb2f74e7_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_019f193b-e72b-7447-97f2-3c7fcb2f74e7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7447-97f2-3c7fcb2f74e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" 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_019f193b-e72b-7447-97f2-3c7fcb2f74e7" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_December2027NotesMember_019f193b-e72b-70af-b8e1-29ec175f3843" xlink:href="bsx-20260630.xsd#bsx_December2027NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_December2027NotesMember_019f193b-e72b-70af-b8e1-29ec175f3843" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2028SeniorNotesMember_019f193b-e72b-7b7b-badd-03b30df93fe9" xlink:href="bsx-20260630.xsd#bsx_March2028SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2028SeniorNotesMember_019f193b-e72b-7b7b-badd-03b30df93fe9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2028NotesMember_019f193b-e72b-749c-a760-be078d52cfbf" xlink:href="bsx-20260630.xsd#bsx_March2028NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2028NotesMember_019f193b-e72b-749c-a760-be078d52cfbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2029NotesMember_019f193b-e72b-761e-abd3-32b06cff26dc" xlink:href="bsx-20260630.xsd#bsx_March2029NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2029NotesMember_019f193b-e72b-761e-abd3-32b06cff26dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2029EuroSeniorNotesMember_019f193b-e72b-76b1-af40-3b18869966e3" xlink:href="bsx-20260630.xsd#bsx_March2029EuroSeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2029EuroSeniorNotesMember_019f193b-e72b-76b1-af40-3b18869966e3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_June2030NotesMember_019f193b-e72b-738b-a326-91e7971eed8a" xlink:href="bsx-20260630.xsd#bsx_June2030NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_June2030NotesMember_019f193b-e72b-738b-a326-91e7971eed8a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2031NotesMember_019f193b-e72b-74c3-88c7-5f47a3415997" xlink:href="bsx-20260630.xsd#bsx_March2031NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2031NotesMember_019f193b-e72b-74c3-88c7-5f47a3415997" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2031Notes2Member_019f193b-e72b-7e38-8705-92636eca1a54" xlink:href="bsx-20260630.xsd#bsx_March2031Notes2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2031Notes2Member_019f193b-e72b-7e38-8705-92636eca1a54" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2032EuroSeniorNotesMember_019f193b-e72b-7461-8cab-1cf951657e4d" xlink:href="bsx-20260630.xsd#bsx_March2032EuroSeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2032EuroSeniorNotesMember_019f193b-e72b-7461-8cab-1cf951657e4d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2034NotesMember_019f193b-e72b-74b5-a98c-f41f5799a6a6" xlink:href="bsx-20260630.xsd#bsx_March2034NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2034NotesMember_019f193b-e72b-74b5-a98c-f41f5799a6a6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2034Notes2Member_019f193b-e72b-7f43-b8fc-f050f3d92737" xlink:href="bsx-20260630.xsd#bsx_March2034Notes2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2034Notes2Member_019f193b-e72b-7f43-b8fc-f050f3d92737" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_November2035NotesMember_019f193b-e72b-7c37-beec-f6e85db3df51" xlink:href="bsx-20260630.xsd#bsx_November2035NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_November2035NotesMember_019f193b-e72b-7c37-beec-f6e85db3df51" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2039NotesMember_019f193b-e72b-748a-b4c3-d9ed91b4cdc1" xlink:href="bsx-20260630.xsd#bsx_March2039NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2039NotesMember_019f193b-e72b-748a-b4c3-d9ed91b4cdc1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_January2040NotesMember_019f193b-e72b-79fa-8a0a-517c8819a5ab" xlink:href="bsx-20260630.xsd#bsx_January2040NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_January2040NotesMember_019f193b-e72b-79fa-8a0a-517c8819a5ab" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2049NotesMember_019f193b-e72b-7d3e-b4c7-2407646e50fd" xlink:href="bsx-20260630.xsd#bsx_March2049NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_March2049NotesMember_019f193b-e72b-7d3e-b4c7-2407646e50fd" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019f193b-e72b-7480-a8b2-d7e4beb10232" 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_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_us-gaap_SeniorNotesMember_019f193b-e72b-7480-a8b2-d7e4beb10232" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_FinancialLeaseObligationMember_019f193b-e72b-7213-b6a6-e3b3b8de9e34" xlink:href="bsx-20260630.xsd#bsx_FinancialLeaseObligationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7b71-8a4e-8052b628e2a8" xlink:to="loc_bsx_FinancialLeaseObligationMember_019f193b-e72b-7213-b6a6-e3b3b8de9e34" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019f9592-93bc-708f-aa6d-d0c8fd7c3c73" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-739f-846e-d83da99429cc" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019f9592-93bc-708f-aa6d-d0c8fd7c3c73" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019f9592-93bc-708f-aa6d-d0c8fd7c3c73_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019f9592-93bc-708f-aa6d-d0c8fd7c3c73" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019f9592-93bc-708f-aa6d-d0c8fd7c3c73_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019f9593-1de2-7f88-a0d8-fed20eb4dcfc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019f9592-93bc-708f-aa6d-d0c8fd7c3c73" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019f9593-1de2-7f88-a0d8-fed20eb4dcfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019f9593-ede3-7da7-ba42-307297d1292d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019f9593-1de2-7f88-a0d8-fed20eb4dcfc" xlink:to="loc_us-gaap_CommercialPaperMember_019f9593-ede3-7da7-ba42-307297d1292d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f193b-e72b-7263-a052-f3e969b1fba2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_LongTermDebt_019f193b-e72b-7263-a052-f3e969b1fba2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019f193b-e72b-799c-9c7e-327ad27338e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019f193b-e72b-799c-9c7e-327ad27338e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019f193b-e72b-7c86-b631-45ab997f21ac" 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_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_019f193b-e72b-7c86-b631-45ab997f21ac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f193b-e72b-751e-a564-cc45acf177b3" 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_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f193b-e72b-751e-a564-cc45acf177b3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaper_019f9594-998f-7196-a860-dcca6c5c7b11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaper"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_CommercialPaper_019f9594-998f-7196-a860-dcca6c5c7b11" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f9594-998f-75e0-be91-f64c0727ad41" 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_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f9594-998f-75e0-be91-f64c0727ad41" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f9594-998f-70fe-9b7b-5061ddb71184" 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_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f9594-998f-70fe-9b7b-5061ddb71184" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_019f9594-998f-7f4e-8c3b-97a41af50868" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_DebtInstrumentTerm_019f9594-998f-7f4e-8c3b-97a41af50868" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_019f9594-998f-7229-80d4-4e4190d020ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7b7b-9e1c-8d954feec679" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_019f9594-998f-7229-80d4-4e4190d020ef" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsNarrativeDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#ContractualObligationsandCommitmentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" 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_019f193b-e72b-7686-a36f-c1a1ad2741f3" 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_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-7686-a36f-c1a1ad2741f3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72b-7c2a-97fe-5a15736d2f8c" 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_019f193b-e72b-7686-a36f-c1a1ad2741f3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019f193b-e72b-7c2a-97fe-5a15736d2f8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7c2a-97fe-5a15736d2f8c_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_019f193b-e72b-7c2a-97fe-5a15736d2f8c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-7c2a-97fe-5a15736d2f8c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" 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_019f193b-e72b-7c2a-97fe-5a15736d2f8c" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019f193b-e72b-7e79-82f2-e21add657b37" 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_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:to="loc_us-gaap_SeniorNotesMember_019f193b-e72b-7e79-82f2-e21add657b37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_The2025OfferingAggregatePrincipalAmountMember_019f193b-e72b-7289-a5c4-75149a928aad" xlink:href="bsx-20260630.xsd#bsx_The2025OfferingAggregatePrincipalAmountMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:to="loc_bsx_The2025OfferingAggregatePrincipalAmountMember_019f193b-e72b-7289-a5c4-75149a928aad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2031Notes2Member_019f193b-e72b-791b-8718-477e0c6dd783" xlink:href="bsx-20260630.xsd#bsx_March2031Notes2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:to="loc_bsx_March2031Notes2Member_019f193b-e72b-791b-8718-477e0c6dd783" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2034Notes2Member_019f193b-e72b-7a6e-aac9-27419b3975fc" xlink:href="bsx-20260630.xsd#bsx_March2034Notes2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:to="loc_bsx_March2034Notes2Member_019f193b-e72b-7a6e-aac9-27419b3975fc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_A2025EurobondOfferingSNsMember_019f193b-e72b-7946-ac67-0d8d7092c26f" xlink:href="bsx-20260630.xsd#bsx_A2025EurobondOfferingSNsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:to="loc_bsx_A2025EurobondOfferingSNsMember_019f193b-e72b-7946-ac67-0d8d7092c26f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_March2025NotesMember_019f193b-e72b-70f7-bd63-bc388cba17c4" xlink:href="bsx-20260630.xsd#bsx_March2025NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:to="loc_bsx_March2025NotesMember_019f193b-e72b-70f7-bd63-bc388cba17c4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_June2025NotesMember_019f193b-e72b-7b4b-ba69-91556e06f153" xlink:href="bsx-20260630.xsd#bsx_June2025NotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019f193b-e72b-774f-bc13-22652f8e4f88" xlink:to="loc_bsx_June2025NotesMember_019f193b-e72b-7b4b-ba69-91556e06f153" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019f193b-e72b-724c-8158-2fcda251cb03" 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_019f193b-e72b-7686-a36f-c1a1ad2741f3" xlink:to="loc_us-gaap_CreditFacilityAxis_019f193b-e72b-724c-8158-2fcda251cb03" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f193b-e72b-724c-8158-2fcda251cb03_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_019f193b-e72b-724c-8158-2fcda251cb03" xlink:to="loc_us-gaap_CreditFacilityDomain_019f193b-e72b-724c-8158-2fcda251cb03_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019f193b-e72b-70c0-8855-13353efce568" 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_019f193b-e72b-724c-8158-2fcda251cb03" xlink:to="loc_us-gaap_CreditFacilityDomain_019f193b-e72b-70c0-8855-13353efce568" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019f193b-e72b-7b5b-a80c-12ea5a78b2c7" 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_019f193b-e72b-70c0-8855-13353efce568" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019f193b-e72b-7b5b-a80c-12ea5a78b2c7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_A2021RevolvingCreditAgreementMember_019fb464-5f29-74f7-acfa-a2fec063289f" xlink:href="bsx-20260630.xsd#bsx_A2021RevolvingCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019f193b-e72b-70c0-8855-13353efce568" xlink:to="loc_bsx_A2021RevolvingCreditAgreementMember_019fb464-5f29-74f7-acfa-a2fec063289f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CovenantAxis_019f193b-e72b-7475-8a28-db2768dd1050" xlink:href="bsx-20260630.xsd#bsx_CovenantAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-7686-a36f-c1a1ad2741f3" xlink:to="loc_bsx_CovenantAxis_019f193b-e72b-7475-8a28-db2768dd1050" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CovenantDomain_019f193b-e72b-7475-8a28-db2768dd1050_default" xlink:href="bsx-20260630.xsd#bsx_CovenantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bsx_CovenantAxis_019f193b-e72b-7475-8a28-db2768dd1050" xlink:to="loc_bsx_CovenantDomain_019f193b-e72b-7475-8a28-db2768dd1050_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:href="bsx-20260630.xsd#bsx_CovenantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bsx_CovenantAxis_019f193b-e72b-7475-8a28-db2768dd1050" xlink:to="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RequirementAsOfDecember312021AndThroughRemainingTermOfFacilityMember_019f193b-e72b-7658-9c62-62e936929c5c" xlink:href="bsx-20260630.xsd#bsx_RequirementAsOfDecember312021AndThroughRemainingTermOfFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:to="loc_bsx_RequirementAsOfDecember312021AndThroughRemainingTermOfFacilityMember_019f193b-e72b-7658-9c62-62e936929c5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RequirementFourSucceedingQuartersFollowingQualifiedAcquisitionMember_019f193b-e72b-7cd9-94a6-ee76f322804d" xlink:href="bsx-20260630.xsd#bsx_RequirementFourSucceedingQuartersFollowingQualifiedAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:to="loc_bsx_RequirementFourSucceedingQuartersFollowingQualifiedAcquisitionMember_019f193b-e72b-7cd9-94a6-ee76f322804d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RequirementfifthquarterfollowingqualifiedacquisitionMember_019f193b-e72b-7e7b-9176-968430c4bacb" xlink:href="bsx-20260630.xsd#bsx_RequirementfifthquarterfollowingqualifiedacquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:to="loc_bsx_RequirementfifthquarterfollowingqualifiedacquisitionMember_019f193b-e72b-7e7b-9176-968430c4bacb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RequirementSixthQuarterFollowingQualifiedAcquisitionMember_019f193b-e72b-7c57-9e80-08ad2d0fddb0" xlink:href="bsx-20260630.xsd#bsx_RequirementSixthQuarterFollowingQualifiedAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:to="loc_bsx_RequirementSixthQuarterFollowingQualifiedAcquisitionMember_019f193b-e72b-7c57-9e80-08ad2d0fddb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RequirementSeventhQuarterFollowingQualifiedAcquisitionMember_019f193b-e72b-7684-81a9-743a62a8ea75" xlink:href="bsx-20260630.xsd#bsx_RequirementSeventhQuarterFollowingQualifiedAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:to="loc_bsx_RequirementSeventhQuarterFollowingQualifiedAcquisitionMember_019f193b-e72b-7684-81a9-743a62a8ea75" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RequirementEighthQuarterFollowingQualifiedAcquisitionAndThroughRemainingTermOfFacilityMember_019f193b-e72b-70ad-9dc7-87fdea431587" xlink:href="bsx-20260630.xsd#bsx_RequirementEighthQuarterFollowingQualifiedAcquisitionAndThroughRemainingTermOfFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-73a6-ab1a-14649cbe4cbc" xlink:to="loc_bsx_RequirementEighthQuarterFollowingQualifiedAcquisitionAndThroughRemainingTermOfFacilityMember_019f193b-e72b-70ad-9dc7-87fdea431587" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019f193b-e72b-7080-956d-7a8cd364e068" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-7686-a36f-c1a1ad2741f3" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019f193b-e72b-7080-956d-7a8cd364e068" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019f193b-e72b-7080-956d-7a8cd364e068_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019f193b-e72b-7080-956d-7a8cd364e068" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019f193b-e72b-7080-956d-7a8cd364e068_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019f193b-e72b-7025-a26e-238249ffe7ca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019f193b-e72b-7080-956d-7a8cd364e068" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019f193b-e72b-7025-a26e-238249ffe7ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_019f193b-e72b-706d-9ca0-01515ceb4ab9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019f193b-e72b-7025-a26e-238249ffe7ca" xlink:to="loc_us-gaap_CommercialPaperMember_019f193b-e72b-706d-9ca0-01515ceb4ab9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f193b-e72b-72ab-875b-81650a9fb48f" 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_019f193b-e72b-7686-a36f-c1a1ad2741f3" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f193b-e72b-72ab-875b-81650a9fb48f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-72ab-875b-81650a9fb48f_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_019f193b-e72b-72ab-875b-81650a9fb48f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-72ab-875b-81650a9fb48f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7795-95e9-1edea70d9e22" 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_019f193b-e72b-72ab-875b-81650a9fb48f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7795-95e9-1edea70d9e22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_A364DayRevolvingCreditAgreementMember_019f193b-e72b-764d-a60f-84916f2f2ddc" xlink:href="bsx-20260630.xsd#bsx_A364DayRevolvingCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7795-95e9-1edea70d9e22" xlink:to="loc_bsx_A364DayRevolvingCreditAgreementMember_019f193b-e72b-764d-a60f-84916f2f2ddc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_TermLoanCreditAgreementMember_019f193b-e72b-7e32-bd62-78bb1d8a0477" xlink:href="bsx-20260630.xsd#bsx_TermLoanCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7795-95e9-1edea70d9e22" xlink:to="loc_bsx_TermLoanCreditAgreementMember_019f193b-e72b-7e32-bd62-78bb1d8a0477" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_TrancheBLoanMember_019f193b-e72b-7432-bf4c-616d0bbd2c3b" xlink:href="bsx-20260630.xsd#bsx_TrancheBLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_TermLoanCreditAgreementMember_019f193b-e72b-7e32-bd62-78bb1d8a0477" xlink:to="loc_bsx_TrancheBLoanMember_019f193b-e72b-7432-bf4c-616d0bbd2c3b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_TrancheALoanMember_019f193b-e72b-7f66-8302-d8312d14c6fe" xlink:href="bsx-20260630.xsd#bsx_TrancheALoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7795-95e9-1edea70d9e22" xlink:to="loc_bsx_TrancheALoanMember_019f193b-e72b-7f66-8302-d8312d14c6fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f193b-e72b-73b3-8aae-7b85f697fa0d" 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_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f193b-e72b-73b3-8aae-7b85f697fa0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019f193b-e72b-772b-98bc-8b170dd2f0dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_LongTermDebt_019f193b-e72b-772b-98bc-8b170dd2f0dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_MaximumLeverageRatio_019f193b-e72b-7ee5-8825-bfac10825600" xlink:href="bsx-20260630.xsd#bsx_MaximumLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_bsx_MaximumLeverageRatio_019f193b-e72b-7ee5-8825-bfac10825600" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_QualifiedAcquisitionConsideration_019f193b-e72b-7301-a172-faf637ad2ffd" xlink:href="bsx-20260630.xsd#bsx_QualifiedAcquisitionConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_bsx_QualifiedAcquisitionConsideration_019f193b-e72b-7301-a172-faf637ad2ffd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_LegalPaymentsRemainingToBeExcludedFromCalculationOfConsolidatedEbitda_019f193b-e72b-76a9-9332-8d2d6ff100df" xlink:href="bsx-20260630.xsd#bsx_LegalPaymentsRemainingToBeExcludedFromCalculationOfConsolidatedEbitda"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_bsx_LegalPaymentsRemainingToBeExcludedFromCalculationOfConsolidatedEbitda_019f193b-e72b-76a9-9332-8d2d6ff100df" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaper_019f193b-e72b-7b63-bb9f-0fa46fcf128b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommercialPaper"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_CommercialPaper_019f193b-e72b-7b63-bb9f-0fa46fcf128b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f193b-e72b-77c4-b852-84a00be9a47d" 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_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019f193b-e72b-77c4-b852-84a00be9a47d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_019f193b-e72b-7b7b-8696-ece2dfcb7437" 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_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt_019f193b-e72b-7b7b-8696-ece2dfcb7437" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019f193b-e72b-7ab2-a9cc-29deaf4cc1af" 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_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019f193b-e72b-7ab2-a9cc-29deaf4cc1af" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramObligationCurrent_019f193b-e72b-74dd-9173-3b3df9990793" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SupplierFinanceProgramObligationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_SupplierFinanceProgramObligationCurrent_019f193b-e72b-74dd-9173-3b3df9990793" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_019f193b-e72b-79d9-ab7d-25a254e0fc20" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_019f193b-e72b-79d9-ab7d-25a254e0fc20" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_LitigationPaymentExclusionFromEBITDA_019f193b-e72b-78f9-abe5-64bd25801845" xlink:href="bsx-20260630.xsd#bsx_LitigationPaymentExclusionFromEBITDA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7cdc-9750-ee132ab2245f" xlink:to="loc_bsx_LitigationPaymentExclusionFromEBITDA_019f193b-e72b-78f9-abe5-64bd25801845" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsCovenantsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#ContractualObligationsandCommitmentsCovenantsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsCovenantsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7c5e-bda5-4e269cc2253f" 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_019f193b-e72b-7678-8cfc-7d18f99a17af" 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_019f193b-e72b-7c5e-bda5-4e269cc2253f" xlink:to="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-7678-8cfc-7d18f99a17af" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CovenantAxis_019f193b-e72b-7b16-add1-a127217a9102" xlink:href="bsx-20260630.xsd#bsx_CovenantAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-7678-8cfc-7d18f99a17af" xlink:to="loc_bsx_CovenantAxis_019f193b-e72b-7b16-add1-a127217a9102" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CovenantDomain_019f193b-e72b-7b16-add1-a127217a9102_default" xlink:href="bsx-20260630.xsd#bsx_CovenantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bsx_CovenantAxis_019f193b-e72b-7b16-add1-a127217a9102" xlink:to="loc_bsx_CovenantDomain_019f193b-e72b-7b16-add1-a127217a9102_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CovenantDomain_019f193b-e72b-770f-89c6-8429196d32f6" xlink:href="bsx-20260630.xsd#bsx_CovenantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bsx_CovenantAxis_019f193b-e72b-7b16-add1-a127217a9102" xlink:to="loc_bsx_CovenantDomain_019f193b-e72b-770f-89c6-8429196d32f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CurrentRequirementMember_019f193b-e72b-7ede-a9b8-84f0e17fe6e9" xlink:href="bsx-20260630.xsd#bsx_CurrentRequirementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-770f-89c6-8429196d32f6" xlink:to="loc_bsx_CurrentRequirementMember_019f193b-e72b-7ede-a9b8-84f0e17fe6e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ActualCovenantMember_019f193b-e72b-7916-9dee-072747378b70" xlink:href="bsx-20260630.xsd#bsx_ActualCovenantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bsx_CovenantDomain_019f193b-e72b-770f-89c6-8429196d32f6" xlink:to="loc_bsx_ActualCovenantMember_019f193b-e72b-7916-9dee-072747378b70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_MaximumLeverageRatio_019f193b-e72b-7bce-9b65-f406545e05df" xlink:href="bsx-20260630.xsd#bsx_MaximumLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7c5e-bda5-4e269cc2253f" xlink:to="loc_bsx_MaximumLeverageRatio_019f193b-e72b-7bce-9b65-f406545e05df" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsFactoringArrangementsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#ContractualObligationsandCommitmentsFactoringArrangementsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/ContractualObligationsandCommitmentsFactoringArrangementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7df7-ad01-fc529d0f221a" 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_019f193b-e72b-70e1-b073-9aed08189232" 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_019f193b-e72b-7df7-ad01-fc529d0f221a" xlink:to="loc_us-gaap_DebtInstrumentTable_019f193b-e72b-70e1-b073-9aed08189232" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f193b-e72b-7cd8-a3b8-78a4b3f0224f" 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_019f193b-e72b-70e1-b073-9aed08189232" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f193b-e72b-7cd8-a3b8-78a4b3f0224f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7cd8-a3b8-78a4b3f0224f_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_019f193b-e72b-7cd8-a3b8-78a4b3f0224f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7cd8-a3b8-78a4b3f0224f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7eec-b993-f667d7300fd7" 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_019f193b-e72b-7cd8-a3b8-78a4b3f0224f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7eec-b993-f667d7300fd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_EuroDenominatedFactoringArrangementsMember_019f193b-e72b-7b90-b1cd-335aa426d1d9" xlink:href="bsx-20260630.xsd#bsx_EuroDenominatedFactoringArrangementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7eec-b993-f667d7300fd7" xlink:to="loc_bsx_EuroDenominatedFactoringArrangementsMember_019f193b-e72b-7b90-b1cd-335aa426d1d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_YenDenominatedFactoringArrangementsMember_019f193b-e72b-7ac3-ba59-613cff7c448a" xlink:href="bsx-20260630.xsd#bsx_YenDenominatedFactoringArrangementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f193b-e72b-7eec-b993-f667d7300fd7" xlink:to="loc_bsx_YenDenominatedFactoringArrangementsMember_019f193b-e72b-7ac3-ba59-613cff7c448a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferOfFinancialAssetsAccountedForAsSalesAmountDerecognized_019f193b-e72b-74c0-bcb9-c451b07383eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransferOfFinancialAssetsAccountedForAsSalesAmountDerecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7df7-ad01-fc529d0f221a" xlink:to="loc_us-gaap_TransferOfFinancialAssetsAccountedForAsSalesAmountDerecognized_019f193b-e72b-74c0-bcb9-c451b07383eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate_019f193b-e72b-72a6-8e98-c3c8fdcb3959" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f193b-e72b-7df7-ad01-fc529d0f221a" xlink:to="loc_us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate_019f193b-e72b-72a6-8e98-c3c8fdcb3959" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/WeightedAverageSharesOutstandingDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#WeightedAverageSharesOutstandingDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/WeightedAverageSharesOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f193b-e72b-7f90-9ae4-826f011107f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f193b-e72b-7636-bbfc-34a8c69b67bc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f193b-e72b-7f90-9ae4-826f011107f8" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f193b-e72b-7636-bbfc-34a8c69b67bc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f193b-e72b-79c4-8d13-7c632c4b2c16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f193b-e72b-7636-bbfc-34a8c69b67bc" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f193b-e72b-79c4-8d13-7c632c4b2c16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f193b-e72b-79c4-8d13-7c632c4b2c16_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f193b-e72b-79c4-8d13-7c632c4b2c16" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f193b-e72b-79c4-8d13-7c632c4b2c16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f193b-e72b-73e0-9af0-20048f097178" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f193b-e72b-79c4-8d13-7c632c4b2c16" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f193b-e72b-73e0-9af0-20048f097178" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f193b-e72b-791b-b2be-2e14804ffe67" 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_AntidilutiveSecuritiesNameDomain_019f193b-e72b-73e0-9af0-20048f097178" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f193b-e72b-791b-b2be-2e14804ffe67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f193b-e72b-7f43-9339-f05a3380f689" 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_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f193b-e72b-7f90-9ae4-826f011107f8" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f193b-e72b-7f43-9339-f05a3380f689" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_019f193b-e72b-7615-acd7-1e1b2a70fa03" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f193b-e72b-7f90-9ae4-826f011107f8" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_019f193b-e72b-7615-acd7-1e1b2a70fa03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f193b-e72b-79ce-84a8-e064981a7b71" 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_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f193b-e72b-7f90-9ae4-826f011107f8" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f193b-e72b-79ce-84a8-e064981a7b71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f193b-e72b-7899-8915-ebf72630dcbc" 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_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f193b-e72b-7f90-9ae4-826f011107f8" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f193b-e72b-7899-8915-ebf72630dcbc" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/SegmentReportingDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#SegmentReportingDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/SegmentReportingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" 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_019f193b-e72b-7179-a6d8-23f6d025abe8" 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_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f193b-e72b-7179-a6d8-23f6d025abe8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019f193b-e72b-7dfc-af74-a889eea536a6" 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_019f193b-e72b-7179-a6d8-23f6d025abe8" xlink:to="loc_srt_ConsolidationItemsAxis_019f193b-e72b-7dfc-af74-a889eea536a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7dfc-af74-a889eea536a6_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_019f193b-e72b-7dfc-af74-a889eea536a6" xlink:to="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7dfc-af74-a889eea536a6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f193b-e72b-752c-acbc-e6d96f0db221" 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_019f193b-e72b-7dfc-af74-a889eea536a6" xlink:to="loc_srt_ConsolidationItemsDomain_019f193b-e72b-752c-acbc-e6d96f0db221" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019f193b-e72b-7e24-ba94-78a312cafaaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f193b-e72b-752c-acbc-e6d96f0db221" xlink:to="loc_us-gaap_OperatingSegmentsMember_019f193b-e72b-7e24-ba94-78a312cafaaa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_019f193b-e72b-7b68-abfa-dcc9d503ef49" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f193b-e72b-752c-acbc-e6d96f0db221" xlink:to="loc_us-gaap_CorporateNonSegmentMember_019f193b-e72b-7b68-abfa-dcc9d503ef49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7201-a2a8-d00886cc2466" 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_019f193b-e72b-7179-a6d8-23f6d025abe8" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7201-a2a8-d00886cc2466" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-7201-a2a8-d00886cc2466_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_019f193b-e72b-7201-a2a8-d00886cc2466" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-7201-a2a8-d00886cc2466_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-79a3-b312-e14fe2d986e1" 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_019f193b-e72b-7201-a2a8-d00886cc2466" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-79a3-b312-e14fe2d986e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_MedsurgMember_019f193b-e72b-75f0-a8c8-76d9d106414b" xlink:href="bsx-20260630.xsd#bsx_MedsurgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-79a3-b312-e14fe2d986e1" xlink:to="loc_bsx_MedsurgMember_019f193b-e72b-75f0-a8c8-76d9d106414b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CardiovascularMember_019f193b-e72b-7d39-b7f6-362c69f7b50a" xlink:href="bsx-20260630.xsd#bsx_CardiovascularMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-79a3-b312-e14fe2d986e1" xlink:to="loc_bsx_CardiovascularMember_019f193b-e72b-7d39-b7f6-362c69f7b50a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RevenuesFromContractsWithCustomersDisaggregatedPerformanceMeasurement_019f193b-e72b-7ec4-ada7-9cd69463d7f3" xlink:href="bsx-20260630.xsd#bsx_RevenuesFromContractsWithCustomersDisaggregatedPerformanceMeasurement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_RevenuesFromContractsWithCustomersDisaggregatedPerformanceMeasurement_019f193b-e72b-7ec4-ada7-9cd69463d7f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ImpactOfForeignCurrencyFluctuationsOnNetSales_019f193b-e72b-7837-aede-904d87546418" xlink:href="bsx-20260630.xsd#bsx_ImpactOfForeignCurrencyFluctuationsOnNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_ImpactOfForeignCurrencyFluctuationsOnNetSales_019f193b-e72b-7837-aede-904d87546418" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f193b-e72b-76e9-b86d-005a9cbb732f" 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_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f193b-e72b-76e9-b86d-005a9cbb732f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CostOfGoodsAndServicesSoldAdjusted_019f193b-e72b-719e-abe7-94ee8157891a" xlink:href="bsx-20260630.xsd#bsx_CostOfGoodsAndServicesSoldAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_CostOfGoodsAndServicesSoldAdjusted_019f193b-e72b-719e-abe7-94ee8157891a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CostOfGoodsAndServicesSoldAdjustedPercentageOfNetSales_019f193b-e72b-7ab8-93a9-c4992e1b9808" xlink:href="bsx-20260630.xsd#bsx_CostOfGoodsAndServicesSoldAdjustedPercentageOfNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_CostOfGoodsAndServicesSoldAdjustedPercentageOfNetSales_019f193b-e72b-7ab8-93a9-c4992e1b9808" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SellingGeneralAndAdministrativeExpenseAdjusted_019f193b-e72b-7a92-af2b-08557881a075" xlink:href="bsx-20260630.xsd#bsx_SellingGeneralAndAdministrativeExpenseAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_SellingGeneralAndAdministrativeExpenseAdjusted_019f193b-e72b-7a92-af2b-08557881a075" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SellingGeneralAndAdministrativeExpenseAdjustedPercentageOfNetSales_019f193b-e72b-7e81-ae35-89a512ea28e0" xlink:href="bsx-20260630.xsd#bsx_SellingGeneralAndAdministrativeExpenseAdjustedPercentageOfNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_SellingGeneralAndAdministrativeExpenseAdjustedPercentageOfNetSales_019f193b-e72b-7e81-ae35-89a512ea28e0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted_019f193b-e72b-7e1b-9d81-3f45b27f4746" xlink:href="bsx-20260630.xsd#bsx_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjusted_019f193b-e72b-7e1b-9d81-3f45b27f4746" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjustedPercentageOfNetSales_019f193b-e72b-784a-81b5-e611c70f3d0d" xlink:href="bsx-20260630.xsd#bsx_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjustedPercentageOfNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCostAdjustedPercentageOfNetSales_019f193b-e72b-784a-81b5-e611c70f3d0d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019f193b-e72b-71ce-9545-eb5903ae74d0" 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_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019f193b-e72b-71ce-9545-eb5903ae74d0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_SegmentReportingOtherSegmentItemAmountPercentageOfNetSales_019f193b-e72b-7159-8ae7-d43d59a80e84" xlink:href="bsx-20260630.xsd#bsx_SegmentReportingOtherSegmentItemAmountPercentageOfNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_SegmentReportingOtherSegmentItemAmountPercentageOfNetSales_019f193b-e72b-7159-8ae7-d43d59a80e84" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_OperatingIncomeLossAdjusted_019f193b-e72b-7a96-b702-3112b8a505e9" xlink:href="bsx-20260630.xsd#bsx_OperatingIncomeLossAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_OperatingIncomeLossAdjusted_019f193b-e72b-7a96-b702-3112b8a505e9" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_OperatingIncomeLossAdjustedPercentageOfNetSales_019f193b-e72b-7c4f-a09e-1b552c9f2c03" xlink:href="bsx-20260630.xsd#bsx_OperatingIncomeLossAdjustedPercentageOfNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_OperatingIncomeLossAdjustedPercentageOfNetSales_019f193b-e72b-7c4f-a09e-1b552c9f2c03" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_019f193b-e72b-7e83-b40c-a6e6eea0b4ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_OperatingExpenses_019f193b-e72b-7e83-b40c-a6e6eea0b4ff" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CertainOtherItems_019f193b-e72b-72f0-8cf0-1102036894b3" xlink:href="bsx-20260630.xsd#bsx_CertainOtherItems"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_bsx_CertainOtherItems_019f193b-e72b-72f0-8cf0-1102036894b3" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019f193b-e72b-7c11-a2a8-b469dcc83c75" 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_SegmentReportingInformationLineItems_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019f193b-e72b-7c11-a2a8-b469dcc83c75" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019f193b-e72b-7a10-9c41-c2881e67bdae" 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_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_OperatingIncomeLoss_019f193b-e72b-7a10-9c41-c2881e67bdae" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019f193b-e72b-7f00-8fac-c240da81f31b" 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_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019f193b-e72b-7f00-8fac-c240da81f31b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019f193b-e72b-75c5-a2c0-5c44d30dc65f" 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_019f193b-e72b-7013-9aee-df4241f887fc" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019f193b-e72b-75c5-a2c0-5c44d30dc65f" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/SegmentReportingDepreciationexpenseDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#SegmentReportingDepreciationexpenseDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/SegmentReportingDepreciationexpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-70ab-a8f0-4ad82fa2cb48" 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_019f193b-e72b-71d7-822d-4d732bc495a1" 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_019f193b-e72b-70ab-a8f0-4ad82fa2cb48" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f193b-e72b-71d7-822d-4d732bc495a1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-760e-9802-ff16a6050fd2" 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_019f193b-e72b-71d7-822d-4d732bc495a1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-760e-9802-ff16a6050fd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-760e-9802-ff16a6050fd2_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_019f193b-e72b-760e-9802-ff16a6050fd2" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-760e-9802-ff16a6050fd2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-7f22-93d8-44462817619d" 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_019f193b-e72b-760e-9802-ff16a6050fd2" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-7f22-93d8-44462817619d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_MedsurgMember_019f193b-e72b-752b-99ee-5f8383552f57" xlink:href="bsx-20260630.xsd#bsx_MedsurgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-7f22-93d8-44462817619d" xlink:to="loc_bsx_MedsurgMember_019f193b-e72b-752b-99ee-5f8383552f57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CardiovascularMember_019f193b-e72b-70a4-9ed4-29ccaf364d9b" xlink:href="bsx-20260630.xsd#bsx_CardiovascularMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-7f22-93d8-44462817619d" xlink:to="loc_bsx_CardiovascularMember_019f193b-e72b-70a4-9ed4-29ccaf364d9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019f193b-e72b-7974-9abe-e1468533d46a" 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_019f193b-e72b-71d7-822d-4d732bc495a1" xlink:to="loc_srt_ConsolidationItemsAxis_019f193b-e72b-7974-9abe-e1468533d46a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7974-9abe-e1468533d46a_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_019f193b-e72b-7974-9abe-e1468533d46a" xlink:to="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7974-9abe-e1468533d46a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7508-bdc2-ead6973efe40" 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_019f193b-e72b-7974-9abe-e1468533d46a" xlink:to="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7508-bdc2-ead6973efe40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019f193b-e72b-7bd1-9761-74528ad508a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7508-bdc2-ead6973efe40" xlink:to="loc_us-gaap_OperatingSegmentsMember_019f193b-e72b-7bd1-9761-74528ad508a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_019f193b-e72b-736a-8430-0230c63cdf06" 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_SegmentReportingInformationLineItems_019f193b-e72b-70ab-a8f0-4ad82fa2cb48" xlink:to="loc_us-gaap_Depreciation_019f193b-e72b-736a-8430-0230c63cdf06" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/SegmentReportingTotalAssetsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#SegmentReportingTotalAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/SegmentReportingTotalAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-722b-95e1-b035922b0e7f" 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_019f193b-e72b-78f2-92e3-e9574cd9bbfb" 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_019f193b-e72b-722b-95e1-b035922b0e7f" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f193b-e72b-78f2-92e3-e9574cd9bbfb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019f193b-e72b-7a57-977a-99f6e803dfa8" 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_019f193b-e72b-78f2-92e3-e9574cd9bbfb" xlink:to="loc_srt_ConsolidationItemsAxis_019f193b-e72b-7a57-977a-99f6e803dfa8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7a57-977a-99f6e803dfa8_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_019f193b-e72b-7a57-977a-99f6e803dfa8" xlink:to="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7a57-977a-99f6e803dfa8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7813-9255-e16916a2ceee" 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_019f193b-e72b-7a57-977a-99f6e803dfa8" xlink:to="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7813-9255-e16916a2ceee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019f193b-e72b-7511-a546-5331706b7b1c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7813-9255-e16916a2ceee" xlink:to="loc_us-gaap_OperatingSegmentsMember_019f193b-e72b-7511-a546-5331706b7b1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_019f193b-e72b-7b83-9757-fb5978874bbb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f193b-e72b-7813-9255-e16916a2ceee" xlink:to="loc_us-gaap_CorporateNonSegmentMember_019f193b-e72b-7b83-9757-fb5978874bbb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7ab2-b619-9e9cfdcbb744" 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_019f193b-e72b-78f2-92e3-e9574cd9bbfb" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7ab2-b619-9e9cfdcbb744" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-7ab2-b619-9e9cfdcbb744_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_019f193b-e72b-7ab2-b619-9e9cfdcbb744" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-7ab2-b619-9e9cfdcbb744_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-785d-a44f-ba4e61808c61" 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_019f193b-e72b-7ab2-b619-9e9cfdcbb744" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-785d-a44f-ba4e61808c61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_MedsurgMember_019f193b-e72b-78bf-b8fa-5bf667818840" xlink:href="bsx-20260630.xsd#bsx_MedsurgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-785d-a44f-ba4e61808c61" xlink:to="loc_bsx_MedsurgMember_019f193b-e72b-78bf-b8fa-5bf667818840" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CardiovascularMember_019f193b-e72b-7172-9f3c-21c2c3dd4025" xlink:href="bsx-20260630.xsd#bsx_CardiovascularMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-785d-a44f-ba4e61808c61" xlink:to="loc_bsx_CardiovascularMember_019f193b-e72b-7172-9f3c-21c2c3dd4025" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_019f193b-e72b-7990-862e-97609cc42662" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f193b-e72b-722b-95e1-b035922b0e7f" xlink:to="loc_us-gaap_OtherAssets_019f193b-e72b-7990-862e-97609cc42662" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f193b-e72b-7b91-aacf-e62209482b10" 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_SegmentReportingInformationLineItems_019f193b-e72b-722b-95e1-b035922b0e7f" xlink:to="loc_us-gaap_Goodwill_019f193b-e72b-7b91-aacf-e62209482b10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019f193b-e72b-7e2c-ad95-1aa7b63b0374" 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_SegmentReportingInformationLineItems_019f193b-e72b-722b-95e1-b035922b0e7f" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019f193b-e72b-7e2c-ad95-1aa7b63b0374" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/SegmentReportingLongLivedAssetsDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#SegmentReportingLongLivedAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/SegmentReportingLongLivedAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f193b-e72b-7274-b214-15e2d3afa212" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019f193b-e72b-754e-88c5-b4d4f90b0479" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f193b-e72b-7274-b214-15e2d3afa212" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019f193b-e72b-754e-88c5-b4d4f90b0479" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019f193b-e72b-7ba1-bd41-e9ffe36dce6d" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019f193b-e72b-754e-88c5-b4d4f90b0479" xlink:to="loc_srt_StatementGeographicalAxis_019f193b-e72b-7ba1-bd41-e9ffe36dce6d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7ba1-bd41-e9ffe36dce6d_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019f193b-e72b-7ba1-bd41-e9ffe36dce6d" xlink:to="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7ba1-bd41-e9ffe36dce6d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f193b-e72b-77f1-8088-116814f7f05b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019f193b-e72b-7ba1-bd41-e9ffe36dce6d" xlink:to="loc_srt_SegmentGeographicalDomain_019f193b-e72b-77f1-8088-116814f7f05b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019f193b-e72b-7193-a37d-e9c452b7fc93" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-77f1-8088-116814f7f05b" xlink:to="loc_country_US_019f193b-e72b-7193-a37d-e9c452b7fc93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_IE_019f193b-e72b-7ea3-a822-85f8cc124211" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_IE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-77f1-8088-116814f7f05b" xlink:to="loc_country_IE_019f193b-e72b-7ea3-a822-85f8cc124211" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CR_019f193b-e72b-7f32-9d32-7d2c215b52df" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_CR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-77f1-8088-116814f7f05b" xlink:to="loc_country_CR_019f193b-e72b-7f32-9d32-7d2c215b52df" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_OtherCountriesMember_019f193b-e72b-73d3-aaf5-bd8380eb6b04" xlink:href="bsx-20260630.xsd#bsx_OtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-77f1-8088-116814f7f05b" xlink:to="loc_bsx_OtherCountriesMember_019f193b-e72b-73d3-aaf5-bd8380eb6b04" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_019f193b-e72b-749b-bd36-4de9d81fb558" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f193b-e72b-7274-b214-15e2d3afa212" xlink:to="loc_us-gaap_NoncurrentAssets_019f193b-e72b-749b-bd36-4de9d81fb558" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019f193b-e72b-72fb-b6e9-86e317ab7c3d" 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_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f193b-e72b-7274-b214-15e2d3afa212" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019f193b-e72b-72fb-b6e9-86e317ab7c3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f193b-e72b-7c1c-a874-7e5127750285" 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_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f193b-e72b-7274-b214-15e2d3afa212" xlink:to="loc_us-gaap_Goodwill_019f193b-e72b-7c1c-a874-7e5127750285" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019f193b-e72b-703c-8e2d-e86d6a89a674" 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_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f193b-e72b-7274-b214-15e2d3afa212" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019f193b-e72b-703c-8e2d-e86d6a89a674" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019f193b-e72b-732e-921a-ebd97cf76d88" 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_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019f193b-e72b-7274-b214-15e2d3afa212" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019f193b-e72b-732e-921a-ebd97cf76d88" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#RevenueDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019f193b-e72b-7293-9159-a8681460864d" 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_019f193b-e72b-7440-a146-56b7e9b30764" 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_019f193b-e72b-7293-9159-a8681460864d" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019f193b-e72b-7440-a146-56b7e9b30764" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019f193b-e72b-7a8d-8974-12426c7a8e10" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f193b-e72b-7440-a146-56b7e9b30764" xlink:to="loc_srt_ProductOrServiceAxis_019f193b-e72b-7a8d-8974-12426c7a8e10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7a8d-8974-12426c7a8e10_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019f193b-e72b-7a8d-8974-12426c7a8e10" xlink:to="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7a8d-8974-12426c7a8e10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019f193b-e72b-7a8d-8974-12426c7a8e10" xlink:to="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_GlobalEndoscopyEndoReportingUnitMember_019f193b-e72b-7f42-a549-5a96727d0b36" xlink:href="bsx-20260630.xsd#bsx_GlobalEndoscopyEndoReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_GlobalEndoscopyEndoReportingUnitMember_019f193b-e72b-7f42-a549-5a96727d0b36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_GlobalUrologyandPelvicHealthReportingUnitMember_019f193b-e72b-70ca-b02d-7ca9403339b0" xlink:href="bsx-20260630.xsd#bsx_GlobalUrologyandPelvicHealthReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_GlobalUrologyandPelvicHealthReportingUnitMember_019f193b-e72b-70ca-b02d-7ca9403339b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_GlobalNeuromodulationNmReportingUnitMember_019f193b-e72b-7425-9831-b4034fcafa21" xlink:href="bsx-20260630.xsd#bsx_GlobalNeuromodulationNmReportingUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_GlobalNeuromodulationNmReportingUnitMember_019f193b-e72b-7425-9831-b4034fcafa21" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_InterventionalCardiologyTherapiesMember_019f193b-e72b-703d-894b-7170a6de5f29" xlink:href="bsx-20260630.xsd#bsx_InterventionalCardiologyTherapiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_InterventionalCardiologyTherapiesMember_019f193b-e72b-703d-894b-7170a6de5f29" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_WatchmanMember_019f193b-e72b-75e3-b30e-44eadcbd1d6c" xlink:href="bsx-20260630.xsd#bsx_WatchmanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_WatchmanMember_019f193b-e72b-75e3-b30e-44eadcbd1d6c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_ElectrophysiologyEPMember_019f193b-e72b-7160-9779-4f95fb5a9ca9" xlink:href="bsx-20260630.xsd#bsx_ElectrophysiologyEPMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_ElectrophysiologyEPMember_019f193b-e72b-7160-9779-4f95fb5a9ca9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CardiacRhythmManagementMember_019f193b-e72b-73c0-983a-595d341ef52d" xlink:href="bsx-20260630.xsd#bsx_CardiacRhythmManagementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_CardiacRhythmManagementMember_019f193b-e72b-73c0-983a-595d341ef52d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_InterventionalOncologyAndEmbolizationMember_019f193b-e72b-7939-84dd-7fd497cc16a9" xlink:href="bsx-20260630.xsd#bsx_InterventionalOncologyAndEmbolizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f193b-e72b-7be8-9980-ca461991ad0a" xlink:to="loc_bsx_InterventionalOncologyAndEmbolizationMember_019f193b-e72b-7939-84dd-7fd497cc16a9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019f193b-e72b-7b91-ad7f-990fcfbc176a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f193b-e72b-7440-a146-56b7e9b30764" xlink:to="loc_srt_StatementGeographicalAxis_019f193b-e72b-7b91-ad7f-990fcfbc176a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7b91-ad7f-990fcfbc176a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019f193b-e72b-7b91-ad7f-990fcfbc176a" xlink:to="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7b91-ad7f-990fcfbc176a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f193b-e72b-776b-b098-950dd23c0702" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019f193b-e72b-7b91-ad7f-990fcfbc176a" xlink:to="loc_srt_SegmentGeographicalDomain_019f193b-e72b-776b-b098-950dd23c0702" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019f193b-e72b-701c-b323-8b92173ad5c8" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-776b-b098-950dd23c0702" xlink:to="loc_country_US_019f193b-e72b-701c-b323-8b92173ad5c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_019f193b-e72b-7be1-9782-137ea808ed76" 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_srt_SegmentGeographicalDomain_019f193b-e72b-776b-b098-950dd23c0702" xlink:to="loc_us-gaap_NonUsMember_019f193b-e72b-7be1-9782-137ea808ed76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7ff9-be7f-701e949f5126" 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_DisaggregationOfRevenueTable_019f193b-e72b-7440-a146-56b7e9b30764" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7ff9-be7f-701e949f5126" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-7ff9-be7f-701e949f5126_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_019f193b-e72b-7ff9-be7f-701e949f5126" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-7ff9-be7f-701e949f5126_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-7f74-874e-82675ad2f4fa" 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_019f193b-e72b-7ff9-be7f-701e949f5126" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-7f74-874e-82675ad2f4fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_MedsurgMember_019f193b-e72b-73df-a3a5-ff73cea0da5b" xlink:href="bsx-20260630.xsd#bsx_MedsurgMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-7f74-874e-82675ad2f4fa" xlink:to="loc_bsx_MedsurgMember_019f193b-e72b-73df-a3a5-ff73cea0da5b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_CardiovascularMember_019f193b-e72b-7ad2-a9c4-c7a083f3c290" xlink:href="bsx-20260630.xsd#bsx_CardiovascularMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-7f74-874e-82675ad2f4fa" xlink:to="loc_bsx_CardiovascularMember_019f193b-e72b-7ad2-a9c4-c7a083f3c290" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f193b-e72b-74b7-a5f2-361cbef39981" 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_019f193b-e72b-7293-9159-a8681460864d" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f193b-e72b-74b7-a5f2-361cbef39981" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/RevenueRevenuebyGeographyDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#RevenueRevenuebyGeographyDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/RevenueRevenuebyGeographyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019f193b-e72b-7d23-a98b-a2bd4e0c8398" 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_019f193b-e72b-79c4-8efc-2b2b1231b9e5" 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_019f193b-e72b-7d23-a98b-a2bd4e0c8398" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019f193b-e72b-79c4-8efc-2b2b1231b9e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019f193b-e72b-7af8-ac17-cfb83a58f301" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f193b-e72b-79c4-8efc-2b2b1231b9e5" xlink:to="loc_srt_StatementGeographicalAxis_019f193b-e72b-7af8-ac17-cfb83a58f301" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7af8-ac17-cfb83a58f301_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019f193b-e72b-7af8-ac17-cfb83a58f301" xlink:to="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7af8-ac17-cfb83a58f301_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7466-8b7a-2daa2a2ab0d8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019f193b-e72b-7af8-ac17-cfb83a58f301" xlink:to="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7466-8b7a-2daa2a2ab0d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019f193b-e72b-7329-a358-c19e656c1a14" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7466-8b7a-2daa2a2ab0d8" xlink:to="loc_country_US_019f193b-e72b-7329-a358-c19e656c1a14" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EMEAMember_019f193b-e72b-7e05-b707-e4212f7e12d2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EMEAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7466-8b7a-2daa2a2ab0d8" xlink:to="loc_us-gaap_EMEAMember_019f193b-e72b-7e05-b707-e4212f7e12d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaPacificMember_019f193b-e72b-775e-9d6c-740b6ff35212" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7466-8b7a-2daa2a2ab0d8" xlink:to="loc_srt_AsiaPacificMember_019f193b-e72b-775e-9d6c-740b6ff35212" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_LatinAmericaandCanadaMember_019f193b-e72b-760f-b825-eb72ea35236b" xlink:href="bsx-20260630.xsd#bsx_LatinAmericaandCanadaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019f193b-e72b-7466-8b7a-2daa2a2ab0d8" xlink:to="loc_bsx_LatinAmericaandCanadaMember_019f193b-e72b-760f-b825-eb72ea35236b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7a30-9913-2ba49a763588" 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_DisaggregationOfRevenueTable_019f193b-e72b-79c4-8efc-2b2b1231b9e5" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f193b-e72b-7a30-9913-2ba49a763588" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-7a30-9913-2ba49a763588_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_019f193b-e72b-7a30-9913-2ba49a763588" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-7a30-9913-2ba49a763588_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f193b-e72b-787f-9002-b623eb320640" 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_019f193b-e72b-7a30-9913-2ba49a763588" xlink:to="loc_us-gaap_SegmentDomain_019f193b-e72b-787f-9002-b623eb320640" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_BSXReportableSegmentsMember_019f193b-e72b-7654-870b-43314265a8bc" xlink:href="bsx-20260630.xsd#bsx_BSXReportableSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f193b-e72b-787f-9002-b623eb320640" xlink:to="loc_bsx_BSXReportableSegmentsMember_019f193b-e72b-7654-870b-43314265a8bc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f193b-e72b-7d92-a8c4-37884a066e1e" 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_019f193b-e72b-7d23-a98b-a2bd4e0c8398" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019f193b-e72b-7d92-a8c4-37884a066e1e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/ChangesinOtherComprehensiveIncomeAOCIRollforwardwithReclassificationDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#ChangesinOtherComprehensiveIncomeAOCIRollforwardwithReclassificationDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/ChangesinOtherComprehensiveIncomeAOCIRollforwardwithReclassificationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019f193b-e72b-70bb-b1b4-d97b26de0139" 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_019f193b-e72b-7b61-b150-68fbb0971387" 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_019f193b-e72b-70bb-b1b4-d97b26de0139" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019f193b-e72b-7b61-b150-68fbb0971387" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72b-7392-b5f3-7c19045aad12" 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_019f193b-e72b-7b61-b150-68fbb0971387" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f193b-e72b-7392-b5f3-7c19045aad12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72b-7392-b5f3-7c19045aad12_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_019f193b-e72b-7392-b5f3-7c19045aad12" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72b-7392-b5f3-7c19045aad12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f193b-e72b-7158-a1ac-842c99b2512d" 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_019f193b-e72b-7392-b5f3-7c19045aad12" xlink:to="loc_us-gaap_EquityComponentDomain_019f193b-e72b-7158-a1ac-842c99b2512d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f193b-e72b-7ac3-9f16-2bc6b5e9ac12" 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_019f193b-e72b-7158-a1ac-842c99b2512d" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f193b-e72b-7ac3-9f16-2bc6b5e9ac12" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f193b-e72b-7e4a-8a8e-c5ea1f10da63" 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_AccumulatedOtherComprehensiveIncomeMember_019f193b-e72b-7ac3-9f16-2bc6b5e9ac12" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019f193b-e72b-7e4a-8a8e-c5ea1f10da63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019f193b-e72b-7646-baf7-3c8dfb5a26b9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f193b-e72b-7ac3-9f16-2bc6b5e9ac12" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019f193b-e72b-7646-baf7-3c8dfb5a26b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019f193b-e72b-7be7-a03d-1ede070308b6" 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_AccumulatedOtherComprehensiveIncomeMember_019f193b-e72b-7ac3-9f16-2bc6b5e9ac12" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019f193b-e72b-7be7-a03d-1ede070308b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019f193b-e72b-75bf-aa1a-f84e80d5835e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019f193b-e72b-70bb-b1b4-d97b26de0139" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019f193b-e72b-75bf-aa1a-f84e80d5835e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f193b-e72b-77db-b694-b93b7552ac39" 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_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019f193b-e72b-75bf-aa1a-f84e80d5835e" xlink:to="loc_us-gaap_StockholdersEquity_019f193b-e72b-77db-b694-b93b7552ac39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019f193b-e72b-74de-95f1-bb21a3dddb5b" 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_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019f193b-e72b-75bf-aa1a-f84e80d5835e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_019f193b-e72b-74de-95f1-bb21a3dddb5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019f193b-e72b-7ce9-8468-6f4179268abc" 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_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019f193b-e72b-75bf-aa1a-f84e80d5835e" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_019f193b-e72b-7ce9-8468-6f4179268abc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f193b-e72b-7ea2-85cd-16aa2e45a9f1" 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_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_019f193b-e72b-75bf-aa1a-f84e80d5835e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019f193b-e72b-7ea2-85cd-16aa2e45a9f1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f193b-e72b-7909-b259-9b16052ac7e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/RestructuringandRelatedActivitiesDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#RestructuringandRelatedActivitiesDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/RestructuringandRelatedActivitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb395-40a7-7c3f-b3b6-d4b74f55a5d7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fb395-40a7-7dd4-a38d-685b4c4c9792" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb395-40a7-7c3f-b3b6-d4b74f55a5d7" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fb395-40a7-7dd4-a38d-685b4c4c9792" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fb395-40a7-7ddc-9c56-5e1c1238bb10" 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_ScheduleOfRestructuringAndRelatedCostsTable_019fb395-40a7-7dd4-a38d-685b4c4c9792" xlink:to="loc_srt_RangeAxis_019fb395-40a7-7ddc-9c56-5e1c1238bb10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fb395-40a7-7ddc-9c56-5e1c1238bb10_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_019fb395-40a7-7ddc-9c56-5e1c1238bb10" xlink:to="loc_srt_RangeMember_019fb395-40a7-7ddc-9c56-5e1c1238bb10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fb395-40a7-7f57-bde6-4b21ffbc5705" 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_019fb395-40a7-7ddc-9c56-5e1c1238bb10" xlink:to="loc_srt_RangeMember_019fb395-40a7-7f57-bde6-4b21ffbc5705" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fb396-070a-7283-a266-5fdd6f4e6071" 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_019fb395-40a7-7f57-bde6-4b21ffbc5705" xlink:to="loc_srt_MinimumMember_019fb396-070a-7283-a266-5fdd6f4e6071" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fb396-33b3-7612-baf5-61234e27def3" 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_019fb395-40a7-7f57-bde6-4b21ffbc5705" xlink:to="loc_srt_MaximumMember_019fb396-33b3-7612-baf5-61234e27def3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fb396-7455-787c-ba94-c9e79192e046" 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_ScheduleOfRestructuringAndRelatedCostsTable_019fb395-40a7-7dd4-a38d-685b4c4c9792" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fb396-7455-787c-ba94-c9e79192e046" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fb396-7455-787c-ba94-c9e79192e046_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_019fb396-7455-787c-ba94-c9e79192e046" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fb396-7455-787c-ba94-c9e79192e046_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fb396-7455-7e54-a204-f4e3f2541e7a" 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_019fb396-7455-787c-ba94-c9e79192e046" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fb396-7455-7e54-a204-f4e3f2541e7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fb396-8aa2-72d9-b65e-b94a2024af1a" 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_019fb396-7455-7e54-a204-f4e3f2541e7a" xlink:to="loc_us-gaap_SubsequentEventMember_019fb396-8aa2-72d9-b65e-b94a2024af1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_019fb394-4ac3-75fd-b301-03cd6b44ba40" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostExpectedCost1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb395-40a7-7c3f-b3b6-d4b74f55a5d7" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_019fb394-4ac3-75fd-b301-03cd6b44ba40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RestructuringAndRelatedCostExpectedCostCash_019fb394-9b01-73f9-92a5-2f3322dec8c4" xlink:href="bsx-20260630.xsd#bsx_RestructuringAndRelatedCostExpectedCostCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb395-40a7-7c3f-b3b6-d4b74f55a5d7" xlink:to="loc_bsx_RestructuringAndRelatedCostExpectedCostCash_019fb394-9b01-73f9-92a5-2f3322dec8c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RestructuringAndRelatedCostExpectedCostCash_019fb395-40a7-77de-9313-39e128e84728" xlink:href="bsx-20260630.xsd#bsx_RestructuringAndRelatedCostExpectedCostCash"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_RestructuringAndRelatedCostExpectedExpenseReduction_019fb395-0bb1-7e8b-afb3-a7577cc4ddf7" xlink:href="bsx-20260630.xsd#bsx_RestructuringAndRelatedCostExpectedExpenseReduction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb395-40a7-7c3f-b3b6-d4b74f55a5d7" xlink:to="loc_bsx_RestructuringAndRelatedCostExpectedExpenseReduction_019fb395-0bb1-7e8b-afb3-a7577cc4ddf7" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bostonscientific.com/role/RestructuringandRelatedActivitiesTypeofCostDetails" xlink:type="simple" xlink:href="bsx-20260630.xsd#RestructuringandRelatedActivitiesTypeofCostDetails"/>
  <link:definitionLink xlink:role="http://www.bostonscientific.com/role/RestructuringandRelatedActivitiesTypeofCostDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb397-82f0-7112-9585-09d762e8a8a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fb397-82f0-7f0a-9e31-c431018545fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb397-82f0-7112-9585-09d762e8a8a2" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fb397-82f0-7f0a-9e31-c431018545fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019fb397-82f0-74b3-8622-58e14694bc0c" 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_ScheduleOfRestructuringAndRelatedCostsTable_019fb397-82f0-7f0a-9e31-c431018545fa" xlink:to="loc_srt_RangeAxis_019fb397-82f0-74b3-8622-58e14694bc0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fb397-82f0-74b3-8622-58e14694bc0c_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_019fb397-82f0-74b3-8622-58e14694bc0c" xlink:to="loc_srt_RangeMember_019fb397-82f0-74b3-8622-58e14694bc0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019fb397-82f0-7914-aea1-f8caccf85216" 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_019fb397-82f0-74b3-8622-58e14694bc0c" xlink:to="loc_srt_RangeMember_019fb397-82f0-7914-aea1-f8caccf85216" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019fb397-82f0-74a4-8a14-70a8355adb78" 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_019fb397-82f0-7914-aea1-f8caccf85216" xlink:to="loc_srt_MaximumMember_019fb397-82f0-74a4-8a14-70a8355adb78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019fb397-d7a1-7f55-9cfe-b46c4be9c63c" 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_019fb397-82f0-7914-aea1-f8caccf85216" xlink:to="loc_srt_MinimumMember_019fb397-d7a1-7f55-9cfe-b46c4be9c63c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019fb397-82f0-7de5-b239-8dc546a278c5" 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_ScheduleOfRestructuringAndRelatedCostsTable_019fb397-82f0-7f0a-9e31-c431018545fa" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019fb397-82f0-7de5-b239-8dc546a278c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fb397-82f0-7de5-b239-8dc546a278c5_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_019fb397-82f0-7de5-b239-8dc546a278c5" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fb397-82f0-7de5-b239-8dc546a278c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019fb397-82f0-7aa0-87f8-8e56224eae1d" 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_019fb397-82f0-7de5-b239-8dc546a278c5" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019fb397-82f0-7aa0-87f8-8e56224eae1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019fb397-82f0-759e-ad0a-14e94e4f16a0" 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_019fb397-82f0-7aa0-87f8-8e56224eae1d" xlink:to="loc_us-gaap_SubsequentEventMember_019fb397-82f0-759e-ad0a-14e94e4f16a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019fb397-82f0-708a-9ec9-08a16f8f268d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019fb397-82f0-7f0a-9e31-c431018545fa" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019fb397-82f0-708a-9ec9-08a16f8f268d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019fb397-82f0-708a-9ec9-08a16f8f268d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019fb397-82f0-708a-9ec9-08a16f8f268d" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019fb397-82f0-708a-9ec9-08a16f8f268d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019fb397-82f0-7ed0-b1f5-f48c3214ea65" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019fb397-82f0-708a-9ec9-08a16f8f268d" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019fb397-82f0-7ed0-b1f5-f48c3214ea65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bsx_TransferCostsMember_019fb398-c106-7bf8-ad5e-047090fc6bf1" xlink:href="bsx-20260630.xsd#bsx_TransferCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019fb397-82f0-7ed0-b1f5-f48c3214ea65" xlink:to="loc_bsx_TransferCostsMember_019fb398-c106-7bf8-ad5e-047090fc6bf1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OneTimeTerminationBenefitsMember_019fb399-2de8-799e-b9b1-ef7878e07c92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OneTimeTerminationBenefitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019fb397-82f0-7ed0-b1f5-f48c3214ea65" xlink:to="loc_us-gaap_OneTimeTerminationBenefitsMember_019fb399-2de8-799e-b9b1-ef7878e07c92" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringMember_019fb399-5c88-7e70-aa63-bed78b9e0172" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherRestructuringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019fb397-82f0-7ed0-b1f5-f48c3214ea65" xlink:to="loc_us-gaap_OtherRestructuringMember_019fb399-5c88-7e70-aa63-bed78b9e0172" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_019fb397-82f0-7740-8c50-e74412e522ec" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestructuringAndRelatedCostExpectedCost1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019fb397-82f0-7112-9585-09d762e8a8a2" xlink:to="loc_us-gaap_RestructuringAndRelatedCostExpectedCost1_019fb397-82f0-7740-8c50-e74412e522ec" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
