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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:91386d08-217c-49f3-b5f5-0bf51b834dc5,g:0ec81cd1-f936-4ce8-bb0b-d3c7bf9dcb39-->
<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.kadant.com/role/ConsolidatedStatementofStockholdersEquity" xlink:type="simple" xlink:href="kai-20260103.xsd#ConsolidatedStatementofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/ConsolidatedStatementofStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_67fdb415-8c20-45a2-899f-070825fd3d42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_67efef2c-801b-44d8-87f3-daa7a6b5220a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_67fdb415-8c20-45a2-899f-070825fd3d42" xlink:to="loc_us-gaap_StatementTable_67efef2c-801b-44d8-87f3-daa7a6b5220a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_e611a8fa-b5be-4ae8-ab23-a640f656a5ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_67efef2c-801b-44d8-87f3-daa7a6b5220a" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_e611a8fa-b5be-4ae8-ab23-a640f656a5ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_e611a8fa-b5be-4ae8-ab23-a640f656a5ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e611a8fa-b5be-4ae8-ab23-a640f656a5ea" xlink:to="loc_us-gaap_EquityComponentDomain_e611a8fa-b5be-4ae8-ab23-a640f656a5ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e611a8fa-b5be-4ae8-ab23-a640f656a5ea" xlink:to="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_321ef392-9808-43db-b656-ab5d6fa2ae8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:to="loc_us-gaap_CommonStockMember_321ef392-9808-43db-b656-ab5d6fa2ae8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_e629f783-ab51-41c2-829e-68806f9f3261" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_e629f783-ab51-41c2-829e-68806f9f3261" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_aeb28020-3678-4686-a426-c69e92e339ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:to="loc_us-gaap_RetainedEarningsMember_aeb28020-3678-4686-a426-c69e92e339ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_ba06d3d3-41dd-4122-8515-dd7f1f20eaa8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:to="loc_us-gaap_TreasuryStockCommonMember_ba06d3d3-41dd-4122-8515-dd7f1f20eaa8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_21ba1a72-e763-4559-bd53-d7ceaa130e21" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_21ba1a72-e763-4559-bd53-d7ceaa130e21" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_186576bc-7705-4b26-8b31-2b6830810f16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_17981001-d1ec-4eea-b850-b6dc28cdfe98" xlink:to="loc_us-gaap_NoncontrollingInterestMember_186576bc-7705-4b26-8b31-2b6830810f16" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_67fdb415-8c20-45a2-899f-070825fd3d42" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_1f1687fb-235a-45dd-b394-85b440a916b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_1f1687fb-235a-45dd-b394-85b440a916b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_e57c81a3-0da7-4abd-b7be-ac7800bc3b36" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_TreasuryStockCommonShares_e57c81a3-0da7-4abd-b7be-ac7800bc3b36" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_c42c0a62-49ef-4db6-9f2d-8576bcc61f93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_c42c0a62-49ef-4db6-9f2d-8576bcc61f93" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_0fb9473f-8e82-42fd-a034-42decefac442" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_ProfitLoss_0fb9473f-8e82-42fd-a034-42decefac442" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_1a6305bd-2afb-47d8-861c-1d1063ea6a30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_Dividends_1a6305bd-2afb-47d8-861c-1d1063ea6a30" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_2cde8f73-8101-450c-98b1-51b060289320" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_2cde8f73-8101-450c-98b1-51b060289320" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_39b6c633-deb8-409c-8441-96e8e3723723" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_39b6c633-deb8-409c-8441-96e8e3723723" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_c8b25f44-3af1-4003-ac99-82a67adf4cbd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_c8b25f44-3af1-4003-ac99-82a67adf4cbd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_e8713a49-da88-4898-9669-0428ea6e7f6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_e8713a49-da88-4898-9669-0428ea6e7f6e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromRedemptions_3f2cef05-71e0-4f8b-9155-55cea80e761e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestDecreaseFromRedemptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromRedemptions_3f2cef05-71e0-4f8b-9155-55cea80e761e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_c48038ea-eda1-4a06-9b94-69d17840c659" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_105502cd-33d5-43aa-93dd-70244e9b1530" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_c48038ea-eda1-4a06-9b94-69d17840c659" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_88322c49-317e-4357-bcad-5b98da62cb85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_6750229d-8b12-4e5f-9d82-37ddf7cabc8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_fbf2b20e-3479-4bf0-8925-7359f881890e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#NatureofOperationsandSummaryofSignificantAccountingPoliciesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_7af91283-3d2e-4ef8-b48d-e5c64c945053_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:to="loc_srt_OwnershipDomain_7af91283-3d2e-4ef8-b48d-e5c64c945053_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_6e4601ae-bf83-4f58-8e49-5ee522d4b45b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:to="loc_srt_OwnershipDomain_6e4601ae-bf83-4f58-8e49-5ee522d4b45b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ItalianCompanyMember_87aa6dd0-c187-4979-b144-135786071549" xlink:href="kai-20260103.xsd#kai_ItalianCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_6e4601ae-bf83-4f58-8e49-5ee522d4b45b" xlink:to="loc_kai_ItalianCompanyMember_87aa6dd0-c187-4979-b144-135786071549" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_73b44903-0664-4766-885f-e4cb475287d9_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_73b44903-0664-4766-885f-e4cb475287d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_30cad713-37e4-4eec-8a59-d97778347010" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_30cad713-37e4-4eec-8a59-d97778347010" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_JointVentureWithItalianCompanyMember_2c355956-63d7-4d68-ab97-2873c5a4104e" xlink:href="kai-20260103.xsd#kai_JointVentureWithItalianCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_30cad713-37e4-4eec-8a59-d97778347010" xlink:to="loc_kai_JointVentureWithItalianCompanyMember_2c355956-63d7-4d68-ab97-2873c5a4104e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e92a62d5-ef3f-42ed-a794-89fefc2d8e68_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e92a62d5-ef3f-42ed-a794-89fefc2d8e68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_KeyKnifeIncMember_aee21eb1-7184-411a-9448-47cb881ae559" xlink:href="kai-20260103.xsd#kai_KeyKnifeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:to="loc_kai_KeyKnifeIncMember_aee21eb1-7184-411a-9448-47cb881ae559" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2024AcquisitionsMember_019c2d13-2ab5-7155-b471-5452c04e1df7" xlink:href="kai-20260103.xsd#kai_A2024AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:to="loc_kai_A2024AcquisitionsMember_019c2d13-2ab5-7155-b471-5452c04e1df7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2025AcquisitionsMember_019caf4c-df6f-7574-a0c8-6b24175ffb58" xlink:href="kai-20260103.xsd#kai_A2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:to="loc_kai_A2025AcquisitionsMember_019caf4c-df6f-7574-a0c8-6b24175ffb58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_987442fc-319d-479f-8b1e-7519694fa105_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_987442fc-319d-479f-8b1e-7519694fa105_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_cd3e3f6a-bf8a-4a20-8090-36543d9447c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_cd3e3f6a-bf8a-4a20-8090-36543d9447c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_064f2dfd-0159-416d-bcfd-112cbca9f29e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_cd3e3f6a-bf8a-4a20-8090-36543d9447c7" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_064f2dfd-0159-416d-bcfd-112cbca9f29e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b5dd2e5c-786f-48bc-8563-8aadb09db81d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:to="loc_srt_ProductsAndServicesDomain_b5dd2e5c-786f-48bc-8563-8aadb09db81d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a54b007f-45e2-43a9-a9da-919c72beb19f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:to="loc_srt_ProductsAndServicesDomain_a54b007f-45e2-43a9-a9da-919c72beb19f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_CertainCapitalContractsMember_a9e87146-ded4-43f5-8657-df5b037b6c48" xlink:href="kai-20260103.xsd#kai_CertainCapitalContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_a54b007f-45e2-43a9-a9da-919c72beb19f" xlink:to="loc_kai_CertainCapitalContractsMember_a9e87146-ded4-43f5-8657-df5b037b6c48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_33993625-94bc-40c4-b8df-c82c0a4794ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_33993625-94bc-40c4-b8df-c82c0a4794ba" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019c9880-7167-7795-987b-94c45ee8a6b1_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:to="loc_srt_SegmentGeographicalDomain_019c9880-7167-7795-987b-94c45ee8a6b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019c9880-7167-7608-b6cc-68796ce89a57" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:to="loc_srt_SegmentGeographicalDomain_019c9880-7167-7608-b6cc-68796ce89a57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_019c9880-7167-748a-937f-a017fff54afe" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019c9880-7167-7608-b6cc-68796ce89a57" xlink:to="loc_country_CN_019c9880-7167-748a-937f-a017fff54afe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-7380-b0d7-107ce4346b89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-7380-b0d7-107ce4346b89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-797d-ae7a-1677f25f930f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-797d-ae7a-1677f25f930f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndBuildingMember_019c9880-7167-7863-9859-8b2c4e12afc6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandAndBuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-797d-ae7a-1677f25f930f" xlink:to="loc_us-gaap_LandAndBuildingMember_019c9880-7167-7863-9859-8b2c4e12afc6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_7f4718e4-0704-4292-9a2b-caef18394026" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_NumberOfReportableSegments_7f4718e4-0704-4292-9a2b-caef18394026" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_17fd8c1b-7cf9-4895-ad09-84d368d415ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_17fd8c1b-7cf9-4895-ad09-84d368d415ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NumberOfSubsidiariesInterestAcquired_f0715e12-fc8c-4566-9785-68a8548a0369" xlink:href="kai-20260103.xsd#kai_NumberOfSubsidiariesInterestAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NumberOfSubsidiariesInterestAcquired_f0715e12-fc8c-4566-9785-68a8548a0369" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NumberOfSubsidiariesRemainingInterestAcquired_51e00ae0-4bef-4859-8c42-8b31cad1153d" xlink:href="kai-20260103.xsd#kai_NumberOfSubsidiariesRemainingInterestAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NumberOfSubsidiariesRemainingInterestAcquired_51e00ae0-4bef-4859-8c42-8b31cad1153d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_8b4c654e-0f07-48d9-a542-326ee31d9016" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_8b4c654e-0f07-48d9-a542-326ee31d9016" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NoncontrollingInterestOptionToPurchaseRemainingOwnershipPercentage_11d05f1a-bd52-4c37-87af-80298d6b198b" xlink:href="kai-20260103.xsd#kai_NoncontrollingInterestOptionToPurchaseRemainingOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NoncontrollingInterestOptionToPurchaseRemainingOwnershipPercentage_11d05f1a-bd52-4c37-87af-80298d6b198b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_59241f7c-2651-4ab4-8071-c8ccd9526493" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_59241f7c-2651-4ab4-8071-c8ccd9526493" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RevenueFromContractWithCustomerEstimatedContractCompletionPeriod_0899f9ee-08c7-4dc7-b351-bb25da1d3ae1" xlink:href="kai-20260103.xsd#kai_RevenueFromContractWithCustomerEstimatedContractCompletionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_RevenueFromContractWithCustomerEstimatedContractCompletionPeriod_0899f9ee-08c7-4dc7-b351-bb25da1d3ae1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_64f0004b-5afd-4f97-9351-4af2887b844a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_64f0004b-5afd-4f97-9351-4af2887b844a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_0830e5fe-23bb-45c2-a527-909347bff354" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_0830e5fe-23bb-45c2-a527-909347bff354" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_f283200a-06ef-496e-b8cb-176a80a54e20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_f283200a-06ef-496e-b8cb-176a80a54e20" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BankAcceptanceMaturityPeriod_b5661c0d-6140-44cd-accd-4feb9b72f2ec" xlink:href="kai-20260103.xsd#kai_BankAcceptanceMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_BankAcceptanceMaturityPeriod_b5661c0d-6140-44cd-accd-4feb9b72f2ec" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DueFromCustomerAcceptances_848de80a-86dc-4314-b23f-9abae4e4b57b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DueFromCustomerAcceptances"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_DueFromCustomerAcceptances_848de80a-86dc-4314-b23f-9abae4e4b57b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_SaleOfPropertyPlantAndEquipmentDownPaymentPercentReceived_019c9880-7167-7692-bc57-9098d858c178" xlink:href="kai-20260103.xsd#kai_SaleOfPropertyPlantAndEquipmentDownPaymentPercentReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_SaleOfPropertyPlantAndEquipmentDownPaymentPercentReceived_019c9880-7167-7692-bc57-9098d858c178" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ProceedsFromSaleOfPropertyPlantAndEquipmentMaximumPeriodForFullReceiptPeriodPostEffectiveDate_019c9880-7167-7532-bc3a-ad5a2c123fbc" xlink:href="kai-20260103.xsd#kai_ProceedsFromSaleOfPropertyPlantAndEquipmentMaximumPeriodForFullReceiptPeriodPostEffectiveDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_ProceedsFromSaleOfPropertyPlantAndEquipmentMaximumPeriodForFullReceiptPeriodPostEffectiveDate_019c9880-7167-7532-bc3a-ad5a2c123fbc" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NontradeReceivablesCurrentNetOfPresentValueDiscount_019c9880-7167-75bd-b7fd-bff6177ab146" xlink:href="kai-20260103.xsd#kai_NontradeReceivablesCurrentNetOfPresentValueDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NontradeReceivablesCurrentNetOfPresentValueDiscount_019c9880-7167-75bd-b7fd-bff6177ab146" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_a13d8c5d-c3b2-497c-a593-ed71bdce5858" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_a13d8c5d-c3b2-497c-a593-ed71bdce5858" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsPurchaseAccountingAdjustments_019caf22-067f-7e83-a1bb-fd62d1f836e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsPurchaseAccountingAdjustments_019caf22-067f-7e83-a1bb-fd62d1f836e4" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_019caf4c-23bd-7912-849a-0a63b87bfda7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_AssetImpairmentCharges_019caf4c-23bd-7912-849a-0a63b87bfda7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019caf1f-1647-7a80-b4fd-c47b07ee858f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019caf1f-1647-7a80-b4fd-c47b07ee858f" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_f7aabc92-9555-458d-aa7f-22b7e576ef85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_f7aabc92-9555-458d-aa7f-22b7e576ef85" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_94647265-5999-4283-ba19-132f509205c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_94647265-5999-4283-ba19-132f509205c0" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_7d566e61-6edb-401a-9052-2d5309188905" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_7d566e61-6edb-401a-9052-2d5309188905" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b80dd04a-d522-4924-82f0-d84d31cc571a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b80dd04a-d522-4924-82f0-d84d31cc571a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_71007b98-8906-48fd-88ad-9e6380c7c88f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_71007b98-8906-48fd-88ad-9e6380c7c88f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_d7f6ceca-2121-49db-b699-0b780930c726" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_d7f6ceca-2121-49db-b699-0b780930c726" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_5daa624f-1ff2-4c51-a652-457626fa6ea9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_5daa624f-1ff2-4c51-a652-457626fa6ea9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_b67d8b6d-e45c-40e7-bb70-7c9e4f8cebe7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_b67d8b6d-e45c-40e7-bb70-7c9e4f8cebe7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_1dae8985-d5a2-40a5-aef0-7ba5d7900b2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_1dae8985-d5a2-40a5-aef0-7ba5d7900b2a" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_4150bee5-0a7f-4eb9-bb52-da27e578e4ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_4150bee5-0a7f-4eb9-bb52-da27e578e4ee" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationAcquisitionCosts_5b96b7df-58f6-4d6e-b556-9c63aaa4b4b2" xlink:href="kai-20260103.xsd#kai_BusinessCombinationAcquisitionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_BusinessCombinationAcquisitionCosts_5b96b7df-58f6-4d6e-b556-9c63aaa4b4b2" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019caf21-0e7d-737d-91ff-610892d38116" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019caf21-0e7d-737d-91ff-610892d38116" xlink:type="arc" order="26"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesAdditionalInformationDetails_1" xlink:type="simple" xlink:href="kai-20260103.xsd#NatureofOperationsandSummaryofSignificantAccountingPoliciesAdditionalInformationDetails_1"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesAdditionalInformationDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_7af91283-3d2e-4ef8-b48d-e5c64c945053_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:to="loc_srt_OwnershipDomain_7af91283-3d2e-4ef8-b48d-e5c64c945053_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_6e4601ae-bf83-4f58-8e49-5ee522d4b45b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_7af91283-3d2e-4ef8-b48d-e5c64c945053" xlink:to="loc_srt_OwnershipDomain_6e4601ae-bf83-4f58-8e49-5ee522d4b45b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ItalianCompanyMember_87aa6dd0-c187-4979-b144-135786071549" xlink:href="kai-20260103.xsd#kai_ItalianCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_6e4601ae-bf83-4f58-8e49-5ee522d4b45b" xlink:to="loc_kai_ItalianCompanyMember_87aa6dd0-c187-4979-b144-135786071549" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_73b44903-0664-4766-885f-e4cb475287d9_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_73b44903-0664-4766-885f-e4cb475287d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_30cad713-37e4-4eec-8a59-d97778347010" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_73b44903-0664-4766-885f-e4cb475287d9" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_30cad713-37e4-4eec-8a59-d97778347010" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_JointVentureWithItalianCompanyMember_2c355956-63d7-4d68-ab97-2873c5a4104e" xlink:href="kai-20260103.xsd#kai_JointVentureWithItalianCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_30cad713-37e4-4eec-8a59-d97778347010" xlink:to="loc_kai_JointVentureWithItalianCompanyMember_2c355956-63d7-4d68-ab97-2873c5a4104e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e92a62d5-ef3f-42ed-a794-89fefc2d8e68_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e92a62d5-ef3f-42ed-a794-89fefc2d8e68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e92a62d5-ef3f-42ed-a794-89fefc2d8e68" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_KeyKnifeIncMember_aee21eb1-7184-411a-9448-47cb881ae559" xlink:href="kai-20260103.xsd#kai_KeyKnifeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:to="loc_kai_KeyKnifeIncMember_aee21eb1-7184-411a-9448-47cb881ae559" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2024AcquisitionsMember_019c2d13-2ab5-7155-b471-5452c04e1df7" xlink:href="kai-20260103.xsd#kai_A2024AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:to="loc_kai_A2024AcquisitionsMember_019c2d13-2ab5-7155-b471-5452c04e1df7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2025AcquisitionsMember_019caf4c-df6f-7574-a0c8-6b24175ffb58" xlink:href="kai-20260103.xsd#kai_A2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4a862317-f313-4660-b1a7-f757dfbeffd2" xlink:to="loc_kai_A2025AcquisitionsMember_019caf4c-df6f-7574-a0c8-6b24175ffb58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_987442fc-319d-479f-8b1e-7519694fa105_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_987442fc-319d-479f-8b1e-7519694fa105_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_cd3e3f6a-bf8a-4a20-8090-36543d9447c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_987442fc-319d-479f-8b1e-7519694fa105" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_cd3e3f6a-bf8a-4a20-8090-36543d9447c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_064f2dfd-0159-416d-bcfd-112cbca9f29e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_cd3e3f6a-bf8a-4a20-8090-36543d9447c7" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_064f2dfd-0159-416d-bcfd-112cbca9f29e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_b5dd2e5c-786f-48bc-8563-8aadb09db81d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:to="loc_srt_ProductsAndServicesDomain_b5dd2e5c-786f-48bc-8563-8aadb09db81d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a54b007f-45e2-43a9-a9da-919c72beb19f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_b5dd2e5c-786f-48bc-8563-8aadb09db81d" xlink:to="loc_srt_ProductsAndServicesDomain_a54b007f-45e2-43a9-a9da-919c72beb19f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_CertainCapitalContractsMember_a9e87146-ded4-43f5-8657-df5b037b6c48" xlink:href="kai-20260103.xsd#kai_CertainCapitalContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_a54b007f-45e2-43a9-a9da-919c72beb19f" xlink:to="loc_kai_CertainCapitalContractsMember_a9e87146-ded4-43f5-8657-df5b037b6c48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019c9880-7167-7795-987b-94c45ee8a6b1_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:to="loc_srt_SegmentGeographicalDomain_019c9880-7167-7795-987b-94c45ee8a6b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019c9880-7167-7608-b6cc-68796ce89a57" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019c9880-7167-7795-987b-94c45ee8a6b1" xlink:to="loc_srt_SegmentGeographicalDomain_019c9880-7167-7608-b6cc-68796ce89a57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_019c9880-7167-748a-937f-a017fff54afe" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019c9880-7167-7608-b6cc-68796ce89a57" xlink:to="loc_country_CN_019c9880-7167-748a-937f-a017fff54afe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_1f895a94-9705-4e4f-956f-8f241130632e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-7380-b0d7-107ce4346b89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-7380-b0d7-107ce4346b89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-797d-ae7a-1677f25f930f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019c9880-7167-7380-b0d7-107ce4346b89" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-797d-ae7a-1677f25f930f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndBuildingMember_019c9880-7167-7863-9859-8b2c4e12afc6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandAndBuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019c9880-7167-797d-ae7a-1677f25f930f" xlink:to="loc_us-gaap_LandAndBuildingMember_019c9880-7167-7863-9859-8b2c4e12afc6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_7f4718e4-0704-4292-9a2b-caef18394026" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_NumberOfReportableSegments_7f4718e4-0704-4292-9a2b-caef18394026" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_17fd8c1b-7cf9-4895-ad09-84d368d415ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_17fd8c1b-7cf9-4895-ad09-84d368d415ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NumberOfSubsidiariesInterestAcquired_f0715e12-fc8c-4566-9785-68a8548a0369" xlink:href="kai-20260103.xsd#kai_NumberOfSubsidiariesInterestAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NumberOfSubsidiariesInterestAcquired_f0715e12-fc8c-4566-9785-68a8548a0369" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NumberOfSubsidiariesRemainingInterestAcquired_51e00ae0-4bef-4859-8c42-8b31cad1153d" xlink:href="kai-20260103.xsd#kai_NumberOfSubsidiariesRemainingInterestAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NumberOfSubsidiariesRemainingInterestAcquired_51e00ae0-4bef-4859-8c42-8b31cad1153d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_8b4c654e-0f07-48d9-a542-326ee31d9016" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MinorityInterestOwnershipPercentageByParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByParent_8b4c654e-0f07-48d9-a542-326ee31d9016" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NoncontrollingInterestOptionToPurchaseRemainingOwnershipPercentage_11d05f1a-bd52-4c37-87af-80298d6b198b" xlink:href="kai-20260103.xsd#kai_NoncontrollingInterestOptionToPurchaseRemainingOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NoncontrollingInterestOptionToPurchaseRemainingOwnershipPercentage_11d05f1a-bd52-4c37-87af-80298d6b198b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_59241f7c-2651-4ab4-8071-c8ccd9526493" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_59241f7c-2651-4ab4-8071-c8ccd9526493" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RevenueFromContractWithCustomerEstimatedContractCompletionPeriod_0899f9ee-08c7-4dc7-b351-bb25da1d3ae1" xlink:href="kai-20260103.xsd#kai_RevenueFromContractWithCustomerEstimatedContractCompletionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_RevenueFromContractWithCustomerEstimatedContractCompletionPeriod_0899f9ee-08c7-4dc7-b351-bb25da1d3ae1" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_64f0004b-5afd-4f97-9351-4af2887b844a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_64f0004b-5afd-4f97-9351-4af2887b844a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_0830e5fe-23bb-45c2-a527-909347bff354" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_0830e5fe-23bb-45c2-a527-909347bff354" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_f283200a-06ef-496e-b8cb-176a80a54e20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_f283200a-06ef-496e-b8cb-176a80a54e20" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BankAcceptanceMaturityPeriod_b5661c0d-6140-44cd-accd-4feb9b72f2ec" xlink:href="kai-20260103.xsd#kai_BankAcceptanceMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_BankAcceptanceMaturityPeriod_b5661c0d-6140-44cd-accd-4feb9b72f2ec" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DueFromCustomerAcceptances_848de80a-86dc-4314-b23f-9abae4e4b57b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DueFromCustomerAcceptances"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_DueFromCustomerAcceptances_848de80a-86dc-4314-b23f-9abae4e4b57b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_SaleOfPropertyPlantAndEquipmentDownPaymentPercentReceived_019c9880-7167-7692-bc57-9098d858c178" xlink:href="kai-20260103.xsd#kai_SaleOfPropertyPlantAndEquipmentDownPaymentPercentReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_SaleOfPropertyPlantAndEquipmentDownPaymentPercentReceived_019c9880-7167-7692-bc57-9098d858c178" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ProceedsFromSaleOfPropertyPlantAndEquipmentMaximumPeriodForFullReceiptPeriodPostEffectiveDate_019c9880-7167-7532-bc3a-ad5a2c123fbc" xlink:href="kai-20260103.xsd#kai_ProceedsFromSaleOfPropertyPlantAndEquipmentMaximumPeriodForFullReceiptPeriodPostEffectiveDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_ProceedsFromSaleOfPropertyPlantAndEquipmentMaximumPeriodForFullReceiptPeriodPostEffectiveDate_019c9880-7167-7532-bc3a-ad5a2c123fbc" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NontradeReceivablesCurrentNetOfPresentValueDiscount_019c9880-7167-75bd-b7fd-bff6177ab146" xlink:href="kai-20260103.xsd#kai_NontradeReceivablesCurrentNetOfPresentValueDiscount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_NontradeReceivablesCurrentNetOfPresentValueDiscount_019c9880-7167-75bd-b7fd-bff6177ab146" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_a13d8c5d-c3b2-497c-a593-ed71bdce5858" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_a13d8c5d-c3b2-497c-a593-ed71bdce5858" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsPurchaseAccountingAdjustments_019caf22-067f-7e83-a1bb-fd62d1f836e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsPurchaseAccountingAdjustments_019caf22-067f-7e83-a1bb-fd62d1f836e4" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_019caf4c-23bd-7912-849a-0a63b87bfda7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_AssetImpairmentCharges_019caf4c-23bd-7912-849a-0a63b87bfda7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019caf1f-1647-7a80-b4fd-c47b07ee858f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_019caf1f-1647-7a80-b4fd-c47b07ee858f" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_f7aabc92-9555-458d-aa7f-22b7e576ef85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_f7aabc92-9555-458d-aa7f-22b7e576ef85" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_94647265-5999-4283-ba19-132f509205c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_94647265-5999-4283-ba19-132f509205c0" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_7d566e61-6edb-401a-9052-2d5309188905" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_7d566e61-6edb-401a-9052-2d5309188905" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b80dd04a-d522-4924-82f0-d84d31cc571a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_b80dd04a-d522-4924-82f0-d84d31cc571a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_71007b98-8906-48fd-88ad-9e6380c7c88f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_71007b98-8906-48fd-88ad-9e6380c7c88f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_d7f6ceca-2121-49db-b699-0b780930c726" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_d7f6ceca-2121-49db-b699-0b780930c726" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_5daa624f-1ff2-4c51-a652-457626fa6ea9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_5daa624f-1ff2-4c51-a652-457626fa6ea9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_b67d8b6d-e45c-40e7-bb70-7c9e4f8cebe7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract_c182cc6d-81ca-4fe3-b59f-631e22dcb201" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_b67d8b6d-e45c-40e7-bb70-7c9e4f8cebe7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_1dae8985-d5a2-40a5-aef0-7ba5d7900b2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_1dae8985-d5a2-40a5-aef0-7ba5d7900b2a" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_4150bee5-0a7f-4eb9-bb52-da27e578e4ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_4150bee5-0a7f-4eb9-bb52-da27e578e4ee" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationAcquisitionCosts_5b96b7df-58f6-4d6e-b556-9c63aaa4b4b2" xlink:href="kai-20260103.xsd#kai_BusinessCombinationAcquisitionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_kai_BusinessCombinationAcquisitionCosts_5b96b7df-58f6-4d6e-b556-9c63aaa4b4b2" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019caf21-0e7d-737d-91ff-610892d38116" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_873cce10-b99c-47fd-b7ae-ecfb6bde39a2" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019caf21-0e7d-737d-91ff-610892d38116" xlink:type="arc" order="26"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesRevenueRecognitionbyProductTypeGeographyandRevenueRecognitionMethodDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#NatureofOperationsandSummaryofSignificantAccountingPoliciesRevenueRecognitionbyProductTypeGeographyandRevenueRecognitionMethodDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesRevenueRecognitionbyProductTypeGeographyandRevenueRecognitionMethodDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_c0e5c075-a2e8-440f-b571-91431f89cd55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_e2868ce0-c48a-4a94-82d2-b4265045ebef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_c0e5c075-a2e8-440f-b571-91431f89cd55" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_e2868ce0-c48a-4a94-82d2-b4265045ebef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_11026ccd-d471-49fe-a08c-c09603cdf548" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e2868ce0-c48a-4a94-82d2-b4265045ebef" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_11026ccd-d471-49fe-a08c-c09603cdf548" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_11026ccd-d471-49fe-a08c-c09603cdf548_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_11026ccd-d471-49fe-a08c-c09603cdf548" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_11026ccd-d471-49fe-a08c-c09603cdf548_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_b94c9aeb-b0c8-4831-bd41-9d2e202b538b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_11026ccd-d471-49fe-a08c-c09603cdf548" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_b94c9aeb-b0c8-4831-bd41-9d2e202b538b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredAtPointInTimeMember_9396b8d1-30a9-436c-8551-262fd72758c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_b94c9aeb-b0c8-4831-bd41-9d2e202b538b" xlink:to="loc_us-gaap_TransferredAtPointInTimeMember_9396b8d1-30a9-436c-8551-262fd72758c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredOverTimeMember_5aa5ba4e-0525-4168-aaa4-15e4d1d2b0a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_b94c9aeb-b0c8-4831-bd41-9d2e202b538b" xlink:to="loc_us-gaap_TransferredOverTimeMember_5aa5ba4e-0525-4168-aaa4-15e4d1d2b0a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_54fbe562-0920-4d37-a334-4d8fe0f26a62" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e2868ce0-c48a-4a94-82d2-b4265045ebef" xlink:to="loc_srt_ProductOrServiceAxis_54fbe562-0920-4d37-a334-4d8fe0f26a62" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_54fbe562-0920-4d37-a334-4d8fe0f26a62_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_54fbe562-0920-4d37-a334-4d8fe0f26a62" xlink:to="loc_srt_ProductsAndServicesDomain_54fbe562-0920-4d37-a334-4d8fe0f26a62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_4b6396ed-6505-4978-a231-3494c112e517" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_54fbe562-0920-4d37-a334-4d8fe0f26a62" xlink:to="loc_srt_ProductsAndServicesDomain_4b6396ed-6505-4978-a231-3494c112e517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_PartsandConsumablesMember_16bd4ad3-cc03-462c-bb65-1c15e22d4cc5" xlink:href="kai-20260103.xsd#kai_PartsandConsumablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_4b6396ed-6505-4978-a231-3494c112e517" xlink:to="loc_kai_PartsandConsumablesMember_16bd4ad3-cc03-462c-bb65-1c15e22d4cc5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_CapitalMember_6da15562-01de-4f0a-bd08-5fbd682953e5" xlink:href="kai-20260103.xsd#kai_CapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_4b6396ed-6505-4978-a231-3494c112e517" xlink:to="loc_kai_CapitalMember_6da15562-01de-4f0a-bd08-5fbd682953e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_450ce6ac-63a7-4f49-9913-481147a18fa8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e2868ce0-c48a-4a94-82d2-b4265045ebef" xlink:to="loc_srt_StatementGeographicalAxis_450ce6ac-63a7-4f49-9913-481147a18fa8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_450ce6ac-63a7-4f49-9913-481147a18fa8_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_450ce6ac-63a7-4f49-9913-481147a18fa8" xlink:to="loc_srt_SegmentGeographicalDomain_450ce6ac-63a7-4f49-9913-481147a18fa8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_40cd7dc7-e534-42ce-8907-327bd53b2f8d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_450ce6ac-63a7-4f49-9913-481147a18fa8" xlink:to="loc_srt_SegmentGeographicalDomain_40cd7dc7-e534-42ce-8907-327bd53b2f8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NorthAmericaMember_c1667026-3f59-464f-9629-88eb80dcff17" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NorthAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_40cd7dc7-e534-42ce-8907-327bd53b2f8d" xlink:to="loc_srt_NorthAmericaMember_c1667026-3f59-464f-9629-88eb80dcff17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EuropeMember_fbd26ed9-5a75-4959-be1c-0a5399598308" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_40cd7dc7-e534-42ce-8907-327bd53b2f8d" xlink:to="loc_srt_EuropeMember_fbd26ed9-5a75-4959-be1c-0a5399598308" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaMember_eaa14917-f87d-4466-aae9-3d97ae03d459" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_AsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_40cd7dc7-e534-42ce-8907-327bd53b2f8d" xlink:to="loc_srt_AsiaMember_eaa14917-f87d-4466-aae9-3d97ae03d459" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RestofWorldMember_b81d5a3e-2a99-48b4-af1f-eb31b3f4e170" xlink:href="kai-20260103.xsd#kai_RestofWorldMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_40cd7dc7-e534-42ce-8907-327bd53b2f8d" xlink:to="loc_kai_RestofWorldMember_b81d5a3e-2a99-48b4-af1f-eb31b3f4e170" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_03447396-3746-4d58-a3b3-ab2364ba121f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_c0e5c075-a2e8-440f-b571-91431f89cd55" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_03447396-3746-4d58-a3b3-ab2364ba121f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#NatureofOperationsandSummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_faa2ddec-f925-4102-ad60-8ec81f4b23cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_debe3bab-a055-4686-95e5-32d10671c0e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_faa2ddec-f925-4102-ad60-8ec81f4b23cc" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_debe3bab-a055-4686-95e5-32d10671c0e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_09d5985d-c60e-4009-8016-b7933ed59b42" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_debe3bab-a055-4686-95e5-32d10671c0e8" xlink:to="loc_srt_RangeAxis_09d5985d-c60e-4009-8016-b7933ed59b42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_09d5985d-c60e-4009-8016-b7933ed59b42_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_09d5985d-c60e-4009-8016-b7933ed59b42" xlink:to="loc_srt_RangeMember_09d5985d-c60e-4009-8016-b7933ed59b42_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5f060550-e3f9-4999-ad63-3d778aab7c28" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_09d5985d-c60e-4009-8016-b7933ed59b42" xlink:to="loc_srt_RangeMember_5f060550-e3f9-4999-ad63-3d778aab7c28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a56cb3ed-bae9-470b-9b8d-c9615b505cae" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5f060550-e3f9-4999-ad63-3d778aab7c28" xlink:to="loc_srt_MinimumMember_a56cb3ed-bae9-470b-9b8d-c9615b505cae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_095fc79a-3cda-4a1d-92f7-caec58027da4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5f060550-e3f9-4999-ad63-3d778aab7c28" xlink:to="loc_srt_MaximumMember_095fc79a-3cda-4a1d-92f7-caec58027da4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_37093e4a-9367-4004-99e2-48ffc54df9ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_debe3bab-a055-4686-95e5-32d10671c0e8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_37093e4a-9367-4004-99e2-48ffc54df9ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_37093e4a-9367-4004-99e2-48ffc54df9ab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_37093e4a-9367-4004-99e2-48ffc54df9ab" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_37093e4a-9367-4004-99e2-48ffc54df9ab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9a3e61b-721a-4ba2-86d6-bb726bff1f3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_37093e4a-9367-4004-99e2-48ffc54df9ab" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9a3e61b-721a-4ba2-86d6-bb726bff1f3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_aaa9922d-2dab-4766-9020-c0dadc14061f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9a3e61b-721a-4ba2-86d6-bb726bff1f3f" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_aaa9922d-2dab-4766-9020-c0dadc14061f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember_4bc19342-eee3-4589-ba2d-08405e3fde6b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9a3e61b-721a-4ba2-86d6-bb726bff1f3f" xlink:to="loc_us-gaap_LandMember_4bc19342-eee3-4589-ba2d-08405e3fde6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_146037cf-cd1c-482b-ac71-ada0bdd38e81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9a3e61b-721a-4ba2-86d6-bb726bff1f3f" xlink:to="loc_us-gaap_BuildingMember_146037cf-cd1c-482b-ac71-ada0bdd38e81" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_MachineryEquipmentAndLeaseholdImprovementsMember_6659714b-f388-4170-9605-17965dfbf0b0" xlink:href="kai-20260103.xsd#kai_MachineryEquipmentAndLeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9a3e61b-721a-4ba2-86d6-bb726bff1f3f" xlink:to="loc_kai_MachineryEquipmentAndLeaseholdImprovementsMember_6659714b-f388-4170-9605-17965dfbf0b0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_b683f65e-90ef-4173-8dc5-a31cab1ea2fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9a3e61b-721a-4ba2-86d6-bb726bff1f3f" xlink:to="loc_us-gaap_ConstructionInProgressMember_b683f65e-90ef-4173-8dc5-a31cab1ea2fb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_1091219c-1e9f-4473-9cf0-d0cefb5c161d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_faa2ddec-f925-4102-ad60-8ec81f4b23cc" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_1091219c-1e9f-4473-9cf0-d0cefb5c161d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_a00d2777-fdc7-4123-9183-9d7f1ed35fa7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_faa2ddec-f925-4102-ad60-8ec81f4b23cc" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_a00d2777-fdc7-4123-9183-9d7f1ed35fa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_8e529d71-cfbe-41a6-bff7-28345be8355a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_faa2ddec-f925-4102-ad60-8ec81f4b23cc" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_8e529d71-cfbe-41a6-bff7-28345be8355a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_5b9f9581-2f4e-4f4a-acc6-5e4db900649f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_faa2ddec-f925-4102-ad60-8ec81f4b23cc" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_5b9f9581-2f4e-4f4a-acc6-5e4db900649f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_PropertyPlantandEquipmentandFinanceLeaseRightofUseAssetDepreciationandAmortizationExpense_d90065d0-b054-499f-9a04-72302dfdbbce" xlink:href="kai-20260103.xsd#kai_PropertyPlantandEquipmentandFinanceLeaseRightofUseAssetDepreciationandAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_faa2ddec-f925-4102-ad60-8ec81f4b23cc" xlink:to="loc_kai_PropertyPlantandEquipmentandFinanceLeaseRightofUseAssetDepreciationandAmortizationExpense_d90065d0-b054-499f-9a04-72302dfdbbce" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesIntangibleAssetsDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#NatureofOperationsandSummaryofSignificantAccountingPoliciesIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_47bf17d7-6398-4573-8e35-9074b291d143" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_f149d700-5880-4099-ac0f-a16cb17f8c5d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_47bf17d7-6398-4573-8e35-9074b291d143" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_f149d700-5880-4099-ac0f-a16cb17f8c5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2b7463f3-f27d-4947-a24d-07af457c6c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_f149d700-5880-4099-ac0f-a16cb17f8c5d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2b7463f3-f27d-4947-a24d-07af457c6c7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2b7463f3-f27d-4947-a24d-07af457c6c7b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2b7463f3-f27d-4947-a24d-07af457c6c7b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2b7463f3-f27d-4947-a24d-07af457c6c7b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fa049f7c-6217-4f2c-b0d1-7cbe5392b53b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2b7463f3-f27d-4947-a24d-07af457c6c7b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fa049f7c-6217-4f2c-b0d1-7cbe5392b53b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_bcb6642e-1224-49d8-b48a-d17de47e1d44" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fa049f7c-6217-4f2c-b0d1-7cbe5392b53b" xlink:to="loc_us-gaap_CustomerRelationshipsMember_bcb6642e-1224-49d8-b48a-d17de47e1d44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntellectualPropertyMember_7a4796a4-71b8-4428-9d6c-a70b0a769cab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntellectualPropertyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fa049f7c-6217-4f2c-b0d1-7cbe5392b53b" xlink:to="loc_us-gaap_IntellectualPropertyMember_7a4796a4-71b8-4428-9d6c-a70b0a769cab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_8c34007d-76fc-4bce-9bef-339ab60308f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fa049f7c-6217-4f2c-b0d1-7cbe5392b53b" xlink:to="loc_us-gaap_TradeNamesMember_8c34007d-76fc-4bce-9bef-339ab60308f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_e42935cc-659b-4e5c-ac78-179b22ba1f65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_fa049f7c-6217-4f2c-b0d1-7cbe5392b53b" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_e42935cc-659b-4e5c-ac78-179b22ba1f65" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_2d218943-1759-48ea-ab49-57973a189951" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_47bf17d7-6398-4573-8e35-9074b291d143" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_2d218943-1759-48ea-ab49-57973a189951" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_35caf0d5-da67-403d-8eab-e1bdc1254431" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_47bf17d7-6398-4573-8e35-9074b291d143" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_35caf0d5-da67-403d-8eab-e1bdc1254431" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FiniteLivedIntangibleAssetsAccumulatedForeignCurrencyTranslationGainLoss_2f297aba-b4d3-4a52-ab79-529eb4305f39" xlink:href="kai-20260103.xsd#kai_FiniteLivedIntangibleAssetsAccumulatedForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_47bf17d7-6398-4573-8e35-9074b291d143" xlink:to="loc_kai_FiniteLivedIntangibleAssetsAccumulatedForeignCurrencyTranslationGainLoss_2f297aba-b4d3-4a52-ab79-529eb4305f39" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_55b31e88-81ec-4341-8b57-39c856085a6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_47bf17d7-6398-4573-8e35-9074b291d143" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_55b31e88-81ec-4341-8b57-39c856085a6f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_26e6ca24-717c-47ef-803e-68335756a73c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_621bb947-5681-4050-9e26-90d159c60f64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_26e6ca24-717c-47ef-803e-68335756a73c" xlink:to="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_621bb947-5681-4050-9e26-90d159c60f64" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_2739b35e-709d-41c3-8162-45a079ce8afd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_621bb947-5681-4050-9e26-90d159c60f64" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_2739b35e-709d-41c3-8162-45a079ce8afd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_2739b35e-709d-41c3-8162-45a079ce8afd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_2739b35e-709d-41c3-8162-45a079ce8afd" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_2739b35e-709d-41c3-8162-45a079ce8afd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_d131ae0c-3d02-41ed-9e1a-080648722950" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_2739b35e-709d-41c3-8162-45a079ce8afd" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_d131ae0c-3d02-41ed-9e1a-080648722950" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_c2222236-c4a9-443f-80ec-4248a7a7c704" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_d131ae0c-3d02-41ed-9e1a-080648722950" xlink:to="loc_us-gaap_TradeNamesMember_c2222236-c4a9-443f-80ec-4248a7a7c704" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_IndefiniteLivedIntangibleAssetsExcludingGoodwillGross_bd4be24b-5798-4d30-9f48-f99e476e672b" xlink:href="kai-20260103.xsd#kai_IndefiniteLivedIntangibleAssetsExcludingGoodwillGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_26e6ca24-717c-47ef-803e-68335756a73c" xlink:to="loc_kai_IndefiniteLivedIntangibleAssetsExcludingGoodwillGross_bd4be24b-5798-4d30-9f48-f99e476e672b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_IndefiniteLivedIntangibleAssetsAccumulatedForeignCurrencyTranslationGainLoss_e03a2679-22a2-407b-bb81-1440a727b92c" xlink:href="kai-20260103.xsd#kai_IndefiniteLivedIntangibleAssetsAccumulatedForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_26e6ca24-717c-47ef-803e-68335756a73c" xlink:to="loc_kai_IndefiniteLivedIntangibleAssetsAccumulatedForeignCurrencyTranslationGainLoss_e03a2679-22a2-407b-bb81-1440a727b92c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_3e36fbb0-eb81-4711-b47f-47de76e185e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_26e6ca24-717c-47ef-803e-68335756a73c" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_3e36fbb0-eb81-4711-b47f-47de76e185e8" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesChangesinCarryingAmountofGoodwillBySegmentDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#NatureofOperationsandSummaryofSignificantAccountingPoliciesChangesinCarryingAmountofGoodwillBySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesChangesinCarryingAmountofGoodwillBySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_1c922e27-cb34-4ad4-83f3-3af5427b2f14" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_8a87c5d9-4615-456c-bae7-29069da1b907" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_1c922e27-cb34-4ad4-83f3-3af5427b2f14" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_8a87c5d9-4615-456c-bae7-29069da1b907" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_c1e2dc35-241e-47b7-a1eb-9255a8d95f3d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_8a87c5d9-4615-456c-bae7-29069da1b907" xlink:to="loc_srt_ConsolidationItemsAxis_c1e2dc35-241e-47b7-a1eb-9255a8d95f3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_c1e2dc35-241e-47b7-a1eb-9255a8d95f3d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_c1e2dc35-241e-47b7-a1eb-9255a8d95f3d" xlink:to="loc_srt_ConsolidationItemsDomain_c1e2dc35-241e-47b7-a1eb-9255a8d95f3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_5c690c39-58bf-4ae3-8b52-6eb4f339c9e6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_c1e2dc35-241e-47b7-a1eb-9255a8d95f3d" xlink:to="loc_srt_ConsolidationItemsDomain_5c690c39-58bf-4ae3-8b52-6eb4f339c9e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_5c2c2da3-022a-46da-a424-8d293d4d9c71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_5c690c39-58bf-4ae3-8b52-6eb4f339c9e6" xlink:to="loc_us-gaap_OperatingSegmentsMember_5c2c2da3-022a-46da-a424-8d293d4d9c71" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_97f3f329-b199-4983-a2f1-015e39c1ec6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_8a87c5d9-4615-456c-bae7-29069da1b907" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_97f3f329-b199-4983-a2f1-015e39c1ec6d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_97f3f329-b199-4983-a2f1-015e39c1ec6d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_97f3f329-b199-4983-a2f1-015e39c1ec6d" xlink:to="loc_us-gaap_SegmentDomain_97f3f329-b199-4983-a2f1-015e39c1ec6d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_b5640eb3-315d-4442-9c8d-20eb1d5ba016" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_97f3f329-b199-4983-a2f1-015e39c1ec6d" xlink:to="loc_us-gaap_SegmentDomain_b5640eb3-315d-4442-9c8d-20eb1d5ba016" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FlowControlMember_e61d4ac9-2e51-4897-839c-c5b9612d30ea" xlink:href="kai-20260103.xsd#kai_FlowControlMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b5640eb3-315d-4442-9c8d-20eb1d5ba016" xlink:to="loc_kai_FlowControlMember_e61d4ac9-2e51-4897-839c-c5b9612d30ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_IndustrialProcessingMember_2372961c-fdac-4240-9d89-8f1aa56f2639" xlink:href="kai-20260103.xsd#kai_IndustrialProcessingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b5640eb3-315d-4442-9c8d-20eb1d5ba016" xlink:to="loc_kai_IndustrialProcessingMember_2372961c-fdac-4240-9d89-8f1aa56f2639" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_MaterialHandlingSystemsMember_3816c8ca-0e40-4767-8f27-87f8c6e7351d" xlink:href="kai-20260103.xsd#kai_MaterialHandlingSystemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b5640eb3-315d-4442-9c8d-20eb1d5ba016" xlink:to="loc_kai_MaterialHandlingSystemsMember_3816c8ca-0e40-4767-8f27-87f8c6e7351d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_1c922e27-cb34-4ad4-83f3-3af5427b2f14" xlink:to="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillGross_6c3953ae-3b37-406e-88e0-5b7de8b3d8be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:to="loc_us-gaap_GoodwillGross_6c3953ae-3b37-406e-88e0-5b7de8b3d8be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_060304b8-216f-4bcc-b5c5-b40d9d632a55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_060304b8-216f-4bcc-b5c5-b40d9d632a55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_95b46ba9-0c86-412d-ab1d-b3f21a3e334a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:to="loc_us-gaap_Goodwill_95b46ba9-0c86-412d-ab1d-b3f21a3e334a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_3f6a6553-1f36-441a-a20e-d231f9c170c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_3f6a6553-1f36-441a-a20e-d231f9c170c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_80a7526e-959f-4bb2-8bd3-02c0723fa4f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_80a7526e-959f-4bb2-8bd3-02c0723fa4f1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_5ca4868a-c5e2-448a-930e-9ecb67233b6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_5ca4868a-c5e2-448a-930e-9ecb67233b6f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPeriodIncreaseDecrease_8d8718ab-5568-43c8-8add-ea6b7d6108bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_86eecfc6-30e5-4543-a37c-e96b2e49df28" xlink:to="loc_us-gaap_GoodwillPeriodIncreaseDecrease_8d8718ab-5568-43c8-8add-ea6b7d6108bf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillGross_736a8353-5514-47ae-82aa-1dfe8a409dd4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_c6dae069-867e-4dff-8dba-71baffbd87c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_1368548d-ff39-4bf4-b96b-ae81839baed1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillGross_bc8b7a68-c01c-41c8-a134-dd1b95c35fb3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_bbb81ab9-104a-4474-b78b-d9595a40f78e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_644f9406-124e-4696-97ed-facc7ad7d811" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesGoodwillByReportingUnitDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#NatureofOperationsandSummaryofSignificantAccountingPoliciesGoodwillByReportingUnitDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/NatureofOperationsandSummaryofSignificantAccountingPoliciesGoodwillByReportingUnitDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_149a672f-4ca3-4327-b8d9-460350de8743" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_1c1419e5-01dd-4e2d-a9e0-a0935fa505cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_149a672f-4ca3-4327-b8d9-460350de8743" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_1c1419e5-01dd-4e2d-a9e0-a0935fa505cf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_e5bf38c9-2faa-499b-a92a-cd02c257970b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_1c1419e5-01dd-4e2d-a9e0-a0935fa505cf" xlink:to="loc_srt_ProductOrServiceAxis_e5bf38c9-2faa-499b-a92a-cd02c257970b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e5bf38c9-2faa-499b-a92a-cd02c257970b_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_e5bf38c9-2faa-499b-a92a-cd02c257970b" xlink:to="loc_srt_ProductsAndServicesDomain_e5bf38c9-2faa-499b-a92a-cd02c257970b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3a23b027-44cd-49d5-bd12-85b46e291b32" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_e5bf38c9-2faa-499b-a92a-cd02c257970b" xlink:to="loc_srt_ProductsAndServicesDomain_3a23b027-44cd-49d5-bd12-85b46e291b32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FluidHandlingMember_8cdac2a7-2d69-4377-87e7-748934517b23" xlink:href="kai-20260103.xsd#kai_FluidHandlingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3a23b027-44cd-49d5-bd12-85b46e291b32" xlink:to="loc_kai_FluidHandlingMember_8cdac2a7-2d69-4377-87e7-748934517b23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_DoctoringCleaningAndFiltrationMember_707616ca-bb17-4b10-95ff-ea67d0103911" xlink:href="kai-20260103.xsd#kai_DoctoringCleaningAndFiltrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3a23b027-44cd-49d5-bd12-85b46e291b32" xlink:to="loc_kai_DoctoringCleaningAndFiltrationMember_707616ca-bb17-4b10-95ff-ea67d0103911" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FiberProcessingMember_71468fe4-48b0-4afe-8f95-e2b83bb838fa" xlink:href="kai-20260103.xsd#kai_FiberProcessingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3a23b027-44cd-49d5-bd12-85b46e291b32" xlink:to="loc_kai_FiberProcessingMember_71468fe4-48b0-4afe-8f95-e2b83bb838fa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_WoodProcessingSystemsSegmentMember_a7bf14a4-aef2-4954-807c-097911e44b47" xlink:href="kai-20260103.xsd#kai_WoodProcessingSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3a23b027-44cd-49d5-bd12-85b46e291b32" xlink:to="loc_kai_WoodProcessingSystemsSegmentMember_a7bf14a4-aef2-4954-807c-097911e44b47" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_MaterialHandlingSystemsMember_026752f9-ea29-4744-a22e-d6d27830c23f" xlink:href="kai-20260103.xsd#kai_MaterialHandlingSystemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3a23b027-44cd-49d5-bd12-85b46e291b32" xlink:to="loc_kai_MaterialHandlingSystemsMember_026752f9-ea29-4744-a22e-d6d27830c23f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_7491182d-16d2-4abf-a4b1-d06e6608c132" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_149a672f-4ca3-4327-b8d9-460350de8743" xlink:to="loc_us-gaap_Goodwill_7491182d-16d2-4abf-a4b1-d06e6608c132" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/AcquisitionsNarrativeDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#AcquisitionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/AcquisitionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_31f94132-ed56-4a2e-a21b-b279a04b1fff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_31f94132-ed56-4a2e-a21b-b279a04b1fff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019b0dff-389b-7d35-bedb-64af50f7f0af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_31f94132-ed56-4a2e-a21b-b279a04b1fff" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019b0dff-389b-7d35-bedb-64af50f7f0af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b0dff-389b-7d35-bedb-64af50f7f0af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019b0dff-389b-7d35-bedb-64af50f7f0af" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b0dff-389b-7d35-bedb-64af50f7f0af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b0dff-389b-7e31-a7aa-8b0b5bd0dcb8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019b0dff-389b-7d35-bedb-64af50f7f0af" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b0dff-389b-7e31-a7aa-8b0b5bd0dcb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2025AcquisitionsMember_019b8229-22d3-7390-9edd-d7d7f4e063e9" xlink:href="kai-20260103.xsd#kai_A2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b0dff-389b-7e31-a7aa-8b0b5bd0dcb8" xlink:to="loc_kai_A2025AcquisitionsMember_019b8229-22d3-7390-9edd-d7d7f4e063e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BabbiniMember_019b8222-004b-7a0e-a70a-f237b4d22cdd" xlink:href="kai-20260103.xsd#kai_BabbiniMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_A2025AcquisitionsMember_019b8229-22d3-7390-9edd-d7d7f4e063e9" xlink:to="loc_kai_BabbiniMember_019b8222-004b-7a0e-a70a-f237b4d22cdd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ClydeIndustriesMember_019b8225-08af-7472-99a2-a33a9b8f2e21" xlink:href="kai-20260103.xsd#kai_ClydeIndustriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_A2025AcquisitionsMember_019b8229-22d3-7390-9edd-d7d7f4e063e9" xlink:to="loc_kai_ClydeIndustriesMember_019b8225-08af-7472-99a2-a33a9b8f2e21" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2024AcquisitionsMember_019b0dff-a216-7485-ab77-516b8213a22d" xlink:href="kai-20260103.xsd#kai_A2024AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b0dff-389b-7e31-a7aa-8b0b5bd0dcb8" xlink:to="loc_kai_A2024AcquisitionsMember_019b0dff-a216-7485-ab77-516b8213a22d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_KeyKnifeIncMember_019b0dff-389b-7af8-9456-e2e6bef36987" xlink:href="kai-20260103.xsd#kai_KeyKnifeIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_A2024AcquisitionsMember_019b0dff-a216-7485-ab77-516b8213a22d" xlink:to="loc_kai_KeyKnifeIncMember_019b0dff-389b-7af8-9456-e2e6bef36987" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_KWSManufacturingCompanyLimitedKWSMember_019b0dff-389b-74e6-b012-0559388e82f6" xlink:href="kai-20260103.xsd#kai_KWSManufacturingCompanyLimitedKWSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_A2024AcquisitionsMember_019b0dff-a216-7485-ab77-516b8213a22d" xlink:to="loc_kai_KWSManufacturingCompanyLimitedKWSMember_019b0dff-389b-74e6-b012-0559388e82f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_DynamicSealingTechnologiesLLCAndAffiliatesDSTIMember_019b0dff-389b-7e3e-b209-1c0f05a45858" xlink:href="kai-20260103.xsd#kai_DynamicSealingTechnologiesLLCAndAffiliatesDSTIMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_A2024AcquisitionsMember_019b0dff-a216-7485-ab77-516b8213a22d" xlink:to="loc_kai_DynamicSealingTechnologiesLLCAndAffiliatesDSTIMember_019b0dff-389b-7e3e-b209-1c0f05a45858" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_OtherAcquisitionsMember_019b0dff-67b7-7933-aa1c-96f54f915ee1" xlink:href="kai-20260103.xsd#kai_OtherAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_A2024AcquisitionsMember_019b0dff-a216-7485-ab77-516b8213a22d" xlink:to="loc_kai_OtherAcquisitionsMember_019b0dff-67b7-7933-aa1c-96f54f915ee1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2023BusinessAcquisitionsMember_019b0e01-7305-7e05-829b-48e4a20dbf84" xlink:href="kai-20260103.xsd#kai_A2023BusinessAcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b0dff-389b-7e31-a7aa-8b0b5bd0dcb8" xlink:to="loc_kai_A2023BusinessAcquisitionsMember_019b0e01-7305-7e05-829b-48e4a20dbf84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019b0dff-a216-7ca3-ac4c-214fe4ffe4d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_31f94132-ed56-4a2e-a21b-b279a04b1fff" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019b0dff-a216-7ca3-ac4c-214fe4ffe4d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019b0dff-a216-7ca3-ac4c-214fe4ffe4d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019b0dff-a216-7ca3-ac4c-214fe4ffe4d2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019b0dff-a216-7ca3-ac4c-214fe4ffe4d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019b0dff-a216-736e-af84-0f88e9abf83a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019b0dff-a216-7ca3-ac4c-214fe4ffe4d2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019b0dff-a216-736e-af84-0f88e9abf83a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019b0dff-a216-70d0-8102-664cc9052467" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019b0dff-a216-736e-af84-0f88e9abf83a" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019b0dff-a216-70d0-8102-664cc9052467" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019b0dff-a216-755e-bda5-08894acc10a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019b0dff-a216-736e-af84-0f88e9abf83a" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_019b0dff-a216-755e-bda5-08894acc10a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_019b0dff-a216-797e-b29e-c7d872b3ad71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019b0dff-a216-736e-af84-0f88e9abf83a" xlink:to="loc_us-gaap_TradeNamesMember_019b0dff-a216-797e-b29e-c7d872b3ad71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentAxis_019b0e01-528e-7a90-aa70-041fff2e9d49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonrecurringAdjustmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_31f94132-ed56-4a2e-a21b-b279a04b1fff" xlink:to="loc_us-gaap_NonrecurringAdjustmentAxis_019b0e01-528e-7a90-aa70-041fff2e9d49" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_019b0e01-528e-7a90-aa70-041fff2e9d49_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_019b0e01-528e-7a90-aa70-041fff2e9d49" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_019b0e01-528e-7a90-aa70-041fff2e9d49_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_019b0e01-528e-7bbf-b8fa-b2d8bd0ab6df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_019b0e01-528e-7a90-aa70-041fff2e9d49" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_019b0e01-528e-7bbf-b8fa-b2d8bd0ab6df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAdjustmentToInventoryMember_019b0e01-528e-79e1-a31e-5c33f4ff554c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAdjustmentToInventoryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_019b0e01-528e-7bbf-b8fa-b2d8bd0ab6df" xlink:to="loc_us-gaap_FairValueAdjustmentToInventoryMember_019b0e01-528e-79e1-a31e-5c33f4ff554c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquisitionRelatedCostsMember_019b0e01-528e-7cc7-8c6d-00b1d6c69d74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquisitionRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_019b0e01-528e-7bbf-b8fa-b2d8bd0ab6df" xlink:to="loc_us-gaap_AcquisitionRelatedCostsMember_019b0e01-528e-7cc7-8c6d-00b1d6c69d74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019b0e01-7305-7cb3-846d-85e423f79823" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_31f94132-ed56-4a2e-a21b-b279a04b1fff" xlink:to="loc_srt_StatementGeographicalAxis_019b0e01-7305-7cb3-846d-85e423f79823" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019b0e01-7305-7cb3-846d-85e423f79823_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019b0e01-7305-7cb3-846d-85e423f79823" xlink:to="loc_srt_SegmentGeographicalDomain_019b0e01-7305-7cb3-846d-85e423f79823_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019b0e01-7305-7787-b0f7-0448c593954f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019b0e01-7305-7cb3-846d-85e423f79823" xlink:to="loc_srt_SegmentGeographicalDomain_019b0e01-7305-7787-b0f7-0448c593954f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_SE_019b0e01-7305-7a0f-b542-e7c0e70600c3" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_SE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019b0e01-7305-7787-b0f7-0448c593954f" xlink:to="loc_country_SE_019b0e01-7305-7a0f-b542-e7c0e70600c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b828f-4b59-7a2b-9899-77dce9c1f388" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_31f94132-ed56-4a2e-a21b-b279a04b1fff" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b828f-4b59-7a2b-9899-77dce9c1f388" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b828f-4b59-7a2b-9899-77dce9c1f388_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b828f-4b59-7a2b-9899-77dce9c1f388" xlink:to="loc_us-gaap_SegmentDomain_019b828f-4b59-7a2b-9899-77dce9c1f388_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b828f-4b59-7feb-84c7-2fa6a22a94fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b828f-4b59-7a2b-9899-77dce9c1f388" xlink:to="loc_us-gaap_SegmentDomain_019b828f-4b59-7feb-84c7-2fa6a22a94fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_IndustrialProcessingMember_019b828f-4b59-7504-9ac0-b687125e9178" xlink:href="kai-20260103.xsd#kai_IndustrialProcessingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b828f-4b59-7feb-84c7-2fa6a22a94fe" xlink:to="loc_kai_IndustrialProcessingMember_019b828f-4b59-7504-9ac0-b687125e9178" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfBusinessesAcquired_019c6a90-e380-7ae6-ab0a-877a7b746a2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfBusinessesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_NumberOfBusinessesAcquired_019c6a90-e380-7ae6-ab0a-877a7b746a2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019c6a90-e380-765d-88bb-1ba1939a28ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019c6a90-e380-765d-88bb-1ba1939a28ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019c6a90-e380-7a3a-97cc-99a214074603" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_Goodwill_019c6a90-e380-7a3a-97cc-99a214074603" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019c6a90-e380-7e78-ae5c-d8e3c9a29df8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_019c6a90-e380-7e78-ae5c-d8e3c9a29df8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019c6a91-2a96-738a-bce4-bf378eb2b4fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019c6a91-2a96-738a-bce4-bf378eb2b4fd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_CostOfGoodsAndServicesSoldPreTaxChargeReversal_019c6a91-6718-7220-8914-3faf4de91181" xlink:href="kai-20260103.xsd#kai_CostOfGoodsAndServicesSoldPreTaxChargeReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_CostOfGoodsAndServicesSoldPreTaxChargeReversal_019c6a91-6718-7220-8914-3faf4de91181" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_SellingGeneralAndAdministrativeExpensePreTaxChargeReversal_019c6a91-6718-70e3-8a99-679b2907e0b8" xlink:href="kai-20260103.xsd#kai_SellingGeneralAndAdministrativeExpensePreTaxChargeReversal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_SellingGeneralAndAdministrativeExpensePreTaxChargeReversal_019c6a91-6718-70e3-8a99-679b2907e0b8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_019c6a91-6718-7906-9835-71e9e7ebeacb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_019c6a91-6718-7906-9835-71e9e7ebeacb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessAcquisitionGoodwillExpectedTaxDeductibleTerm_019c6a91-6718-79d5-95df-811fb8695565" xlink:href="kai-20260103.xsd#kai_BusinessAcquisitionGoodwillExpectedTaxDeductibleTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_BusinessAcquisitionGoodwillExpectedTaxDeductibleTerm_019c6a91-6718-79d5-95df-811fb8695565" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessAcquisitionIntangibleAssetsOtherThanGoodwillExpectedTaxDeductibleAmount_019c6a91-6718-7c32-afa4-5fcaef036020" xlink:href="kai-20260103.xsd#kai_BusinessAcquisitionIntangibleAssetsOtherThanGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_BusinessAcquisitionIntangibleAssetsOtherThanGoodwillExpectedTaxDeductibleAmount_019c6a91-6718-7c32-afa4-5fcaef036020" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessAcquisitionIntangibleAssetsOtherThanGoodwillExpectedTaxDeductibleTerm_019c6a91-6718-7167-a75e-61ff79880853" xlink:href="kai-20260103.xsd#kai_BusinessAcquisitionIntangibleAssetsOtherThanGoodwillExpectedTaxDeductibleTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_BusinessAcquisitionIntangibleAssetsOtherThanGoodwillExpectedTaxDeductibleTerm_019c6a91-6718-7167-a75e-61ff79880853" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019c6a91-6718-7f49-861b-cbd8938719aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019c6a91-6718-7f49-861b-cbd8938719aa" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NumberOfSubsidiariesInterestAcquired_019c6a91-6718-7f23-9aef-224a2f931bca" xlink:href="kai-20260103.xsd#kai_NumberOfSubsidiariesInterestAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_NumberOfSubsidiariesInterestAcquired_019c6a91-6718-7f23-9aef-224a2f931bca" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_019c6a91-6718-7fcf-8209-abc3cdd9d5b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination_019c6a91-6718-7fcf-8209-abc3cdd9d5b1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019c6a91-6718-7e55-9ac3-5407ea417c40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019c6a91-6718-7e55-9ac3-5407ea417c40" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019c6a91-6718-79d4-ba31-725b5b66c0d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019c6a91-6718-79d4-ba31-725b5b66c0d7" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_PaymentToAcquireBusinessesOverdraft_019c6a91-6718-7877-8fb8-ea4b3e067f2c" xlink:href="kai-20260103.xsd#kai_PaymentToAcquireBusinessesOverdraft"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_PaymentToAcquireBusinessesOverdraft_019c6a91-6718-7877-8fb8-ea4b3e067f2c" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationAcquisitionOfSubsidiarySharesFromNoncontrollingInterest_019c6a91-9047-72c0-a3a8-fa42f958bd8f" xlink:href="kai-20260103.xsd#kai_BusinessCombinationAcquisitionOfSubsidiarySharesFromNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_BusinessCombinationAcquisitionOfSubsidiarySharesFromNoncontrollingInterest_019c6a91-9047-72c0-a3a8-fa42f958bd8f" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_019c6a91-9047-7558-b1e2-dc8ab49c7ce1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_019c6a91-9047-7558-b1e2-dc8ab49c7ce1" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationConsiderationTransferredLiabilitiesIncurredTerm_019c6a91-9047-7cd4-8ff4-cd020b916f08" xlink:href="kai-20260103.xsd#kai_BusinessCombinationConsiderationTransferredLiabilitiesIncurredTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_kai_BusinessCombinationConsiderationTransferredLiabilitiesIncurredTerm_019c6a91-9047-7cd4-8ff4-cd020b916f08" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019c6a91-9047-74bd-99ad-b0e4173a8769" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019c6a91-9047-74bd-99ad-b0e4173a8769" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019c6a91-9047-7993-b09a-de0dc2baa1a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019c6a91-9047-7993-b09a-de0dc2baa1a2" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019c6a91-9047-7681-92f6-f2589e0f133e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d29ea03f-f695-499a-85db-58aebb4b1615" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_019c6a91-9047-7681-92f6-f2589e0f133e" xlink:type="arc" order="22"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/AcquisitionsAcquisitionPurchasePriceAllocationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#AcquisitionsAcquisitionPurchasePriceAllocationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/AcquisitionsAcquisitionPurchasePriceAllocationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba1b9d35-86c2-4b0b-b10a-fb6b7f59124e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba1b9d35-86c2-4b0b-b10a-fb6b7f59124e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_358da17e-43f9-40e5-9fca-07c06771cee7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba1b9d35-86c2-4b0b-b10a-fb6b7f59124e" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_358da17e-43f9-40e5-9fca-07c06771cee7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_358da17e-43f9-40e5-9fca-07c06771cee7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_358da17e-43f9-40e5-9fca-07c06771cee7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_358da17e-43f9-40e5-9fca-07c06771cee7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_07f3b8b5-613a-411f-8e3d-efdee126ca98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_358da17e-43f9-40e5-9fca-07c06771cee7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_07f3b8b5-613a-411f-8e3d-efdee126ca98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2025AcquisitionsMember_019c2cdd-4e60-7b04-9271-e66ba29bc6ee" xlink:href="kai-20260103.xsd#kai_A2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_07f3b8b5-613a-411f-8e3d-efdee126ca98" xlink:to="loc_kai_A2025AcquisitionsMember_019c2cdd-4e60-7b04-9271-e66ba29bc6ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2024AcquisitionsMember_27a648b0-aa0d-41ed-a525-288d113cd516" xlink:href="kai-20260103.xsd#kai_A2024AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_07f3b8b5-613a-411f-8e3d-efdee126ca98" xlink:to="loc_kai_A2024AcquisitionsMember_27a648b0-aa0d-41ed-a525-288d113cd516" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de52632c-c509-447c-bc23-c533cc20263e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_ba1b9d35-86c2-4b0b-b10a-fb6b7f59124e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de52632c-c509-447c-bc23-c533cc20263e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_de52632c-c509-447c-bc23-c533cc20263e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de52632c-c509-447c-bc23-c533cc20263e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_de52632c-c509-447c-bc23-c533cc20263e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20362c1d-3076-4f4b-a301-264f88018ae1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_de52632c-c509-447c-bc23-c533cc20263e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20362c1d-3076-4f4b-a301-264f88018ae1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_1d429dcc-3ac4-4640-93f6-6adb59a6f9b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20362c1d-3076-4f4b-a301-264f88018ae1" xlink:to="loc_us-gaap_CustomerRelationshipsMember_1d429dcc-3ac4-4640-93f6-6adb59a6f9b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_1e077a93-6966-4e01-a073-314e8006caff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20362c1d-3076-4f4b-a301-264f88018ae1" xlink:to="loc_us-gaap_TradeNamesMember_1e077a93-6966-4e01-a073-314e8006caff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_4d8111ea-70de-4a5f-a5e6-048f0fece83f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20362c1d-3076-4f4b-a301-264f88018ae1" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_4d8111ea-70de-4a5f-a5e6-048f0fece83f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_7fba9cf5-9f4d-44f4-a892-f96f886fd64f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_20362c1d-3076-4f4b-a301-264f88018ae1" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_7fba9cf5-9f4d-44f4-a892-f96f886fd64f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_019c7c10-a309-78f7-9db4-71e64536f521" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_019c7c10-a309-78f7-9db4-71e64536f521" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_43d1fae9-353d-48d2-a47c-4b2f6bc9b429" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_43d1fae9-353d-48d2-a47c-4b2f6bc9b429" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_4ffce193-b193-492b-8e1f-4dbf823c2b3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_4ffce193-b193-492b-8e1f-4dbf823c2b3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_77a30053-25f6-4f90-9adb-960d4f6e0a9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_77a30053-25f6-4f90-9adb-960d4f6e0a9a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_a09cb8a0-a109-447a-bf13-a3df9d1b23bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_a09cb8a0-a109-447a-bf13-a3df9d1b23bf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_57af15c7-10d8-4f80-826f-e0f329603739" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_57af15c7-10d8-4f80-826f-e0f329603739" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_61c844dc-621a-484a-a49b-658b21be5e2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_61c844dc-621a-484a-a49b-658b21be5e2e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_1fdcad89-73f9-47a2-8d44-7ab2807ccd3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_Goodwill_1fdcad89-73f9-47a2-8d44-7ab2807ccd3a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_22c35915-fa7a-4e58-8fa8-de95e6011087" xlink:href="kai-20260103.xsd#kai_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_kai_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill_22c35915-fa7a-4e58-8fa8-de95e6011087" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_5309c042-e0c3-405a-8b6a-b7f9dba75a85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_5309c042-e0c3-405a-8b6a-b7f9dba75a85" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesCustomerDeposits_c9249e5b-380b-4fad-9d76-0617e1459f11" xlink:href="kai-20260103.xsd#kai_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesCustomerDeposits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_kai_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesCustomerDeposits_c9249e5b-380b-4fad-9d76-0617e1459f11" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_5283259a-ba9d-40be-8b7a-d0c2f64f791c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_5283259a-ba9d-40be-8b7a-d0c2f64f791c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_019c2cd6-e69c-71f0-a26c-4e4024b11c43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_019c2cd6-e69c-71f0-a26c-4e4024b11c43" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_56bfc2d6-59ac-44db-bf7c-604dc61523dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_56bfc2d6-59ac-44db-bf7c-604dc61523dc" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_e777f5c1-70fc-42af-b790-500f682764f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_e777f5c1-70fc-42af-b790-500f682764f8" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_018d314b-4b4c-4fec-b76b-1eab45ad1ff9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_018d314b-4b4c-4fec-b76b-1eab45ad1ff9" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue_03da1be4-bb41-4e04-bdd5-41bea932ec2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionOfLessThan100PercentNoncontrollingInterestFairValue_03da1be4-bb41-4e04-bdd5-41bea932ec2a" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_20718bca-6df4-4ebc-994a-e9ff6a736453" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_20718bca-6df4-4ebc-994a-e9ff6a736453" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_b5b77dbe-a3b2-440c-98c8-71b313ce3a81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferredAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb6b8ced-40ce-4957-88dd-e6df3d19012d" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_b5b77dbe-a3b2-440c-98c8-71b313ce3a81" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_30c36824-5236-4e9d-8078-6a139c2624be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_b5b77dbe-a3b2-440c-98c8-71b313ce3a81" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_30c36824-5236-4e9d-8078-6a139c2624be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationConsiderationTransferredContingentConsiderationFairValueDisclosure_74cc2c24-5dda-427b-91b9-272bafabdb88" xlink:href="kai-20260103.xsd#kai_BusinessCombinationConsiderationTransferredContingentConsiderationFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_b5b77dbe-a3b2-440c-98c8-71b313ce3a81" xlink:to="loc_kai_BusinessCombinationConsiderationTransferredContingentConsiderationFairValueDisclosure_74cc2c24-5dda-427b-91b9-272bafabdb88" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationConsiderationTransferredLiabilitiesIncurredNet_d6be6224-553c-4431-a4ac-235cfb29284e" xlink:href="kai-20260103.xsd#kai_BusinessCombinationConsiderationTransferredLiabilitiesIncurredNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_b5b77dbe-a3b2-440c-98c8-71b313ce3a81" xlink:to="loc_kai_BusinessCombinationConsiderationTransferredLiabilitiesIncurredNet_d6be6224-553c-4431-a4ac-235cfb29284e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_66531618-3faf-4540-a674-7d4514cfd64c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredAbstract_b5b77dbe-a3b2-440c-98c8-71b313ce3a81" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_66531618-3faf-4540-a674-7d4514cfd64c" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/AcquisitionsRevenueandOperatingIncomeDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#AcquisitionsRevenueandOperatingIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/AcquisitionsRevenueandOperatingIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_fc79d3c6-2412-4af4-994d-61342cf307e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_443d93e6-dc1f-4181-a9ad-1d7dda843366" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fc79d3c6-2412-4af4-994d-61342cf307e0" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_443d93e6-dc1f-4181-a9ad-1d7dda843366" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_4c89cb7a-a21c-46ab-abd1-0b29fd30331f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_443d93e6-dc1f-4181-a9ad-1d7dda843366" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_4c89cb7a-a21c-46ab-abd1-0b29fd30331f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4c89cb7a-a21c-46ab-abd1-0b29fd30331f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4c89cb7a-a21c-46ab-abd1-0b29fd30331f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4c89cb7a-a21c-46ab-abd1-0b29fd30331f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0abe9ca6-e68a-4028-a8d3-7184b0c6c9b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4c89cb7a-a21c-46ab-abd1-0b29fd30331f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0abe9ca6-e68a-4028-a8d3-7184b0c6c9b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2025AcquisitionsMember_019c2cdd-a200-71b6-82f8-1b222b247177" xlink:href="kai-20260103.xsd#kai_A2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0abe9ca6-e68a-4028-a8d3-7184b0c6c9b4" xlink:to="loc_kai_A2025AcquisitionsMember_019c2cdd-a200-71b6-82f8-1b222b247177" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2024AcquisitionsMember_229e452a-71ec-42bc-9118-20511df13cd7" xlink:href="kai-20260103.xsd#kai_A2024AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0abe9ca6-e68a-4028-a8d3-7184b0c6c9b4" xlink:to="loc_kai_A2024AcquisitionsMember_229e452a-71ec-42bc-9118-20511df13cd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_c1a9de71-5800-40e8-b8cc-814d9060d43c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fc79d3c6-2412-4af4-994d-61342cf307e0" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_c1a9de71-5800-40e8-b8cc-814d9060d43c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_8443f8f9-1b10-4833-bddd-d6166f09fc90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fc79d3c6-2412-4af4-994d-61342cf307e0" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_8443f8f9-1b10-4833-bddd-d6166f09fc90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessCombinationProFormaInformationAmortizationExpenseWithAcquiredProfitInInventoryAndBacklog_29e5f9a1-b555-4f63-9672-a90e8822ab2c" xlink:href="kai-20260103.xsd#kai_BusinessCombinationProFormaInformationAmortizationExpenseWithAcquiredProfitInInventoryAndBacklog"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_fc79d3c6-2412-4af4-994d-61342cf307e0" xlink:to="loc_kai_BusinessCombinationProFormaInformationAmortizationExpenseWithAcquiredProfitInInventoryAndBacklog_29e5f9a1-b555-4f63-9672-a90e8822ab2c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/AcquisitionsProFormaInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#AcquisitionsProFormaInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/AcquisitionsProFormaInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_5f2961c4-02db-40d2-8cde-ea1bc419d5af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_855db07c-0f87-49d8-abcb-1ce36b6c18a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_5f2961c4-02db-40d2-8cde-ea1bc419d5af" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_855db07c-0f87-49d8-abcb-1ce36b6c18a1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_21153218-6755-41c2-8da4-1a54c6cec796" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_855db07c-0f87-49d8-abcb-1ce36b6c18a1" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_21153218-6755-41c2-8da4-1a54c6cec796" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_21153218-6755-41c2-8da4-1a54c6cec796_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_21153218-6755-41c2-8da4-1a54c6cec796" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_21153218-6755-41c2-8da4-1a54c6cec796_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f9a0bc8a-d239-467b-8759-c6ac8b027464" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_21153218-6755-41c2-8da4-1a54c6cec796" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f9a0bc8a-d239-467b-8759-c6ac8b027464" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2025AcquisitionsMember_019bb2a8-1e25-7d08-9f4a-ce7881a5f2ca" xlink:href="kai-20260103.xsd#kai_A2025AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f9a0bc8a-d239-467b-8759-c6ac8b027464" xlink:to="loc_kai_A2025AcquisitionsMember_019bb2a8-1e25-7d08-9f4a-ce7881a5f2ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_741c0140-ee34-4c45-9303-0a5ddf2d03cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_5f2961c4-02db-40d2-8cde-ea1bc419d5af" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_741c0140-ee34-4c45-9303-0a5ddf2d03cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_51010211-fc19-43fe-a6d3-bf5ca5c5edc0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_5f2961c4-02db-40d2-8cde-ea1bc419d5af" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_51010211-fc19-43fe-a6d3-bf5ca5c5edc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BusinessAcquisitionProFormaEarningsPerShareAbstract_d619bb82-3c88-41f3-a510-23abb4fb7993" xlink:href="kai-20260103.xsd#kai_BusinessAcquisitionProFormaEarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_5f2961c4-02db-40d2-8cde-ea1bc419d5af" xlink:to="loc_kai_BusinessAcquisitionProFormaEarningsPerShareAbstract_d619bb82-3c88-41f3-a510-23abb4fb7993" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_d2972348-f7e8-4097-8701-7c901651e0d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_BusinessAcquisitionProFormaEarningsPerShareAbstract_d619bb82-3c88-41f3-a510-23abb4fb7993" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic_d2972348-f7e8-4097-8701-7c901651e0d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_17367d8e-45b8-40e6-9739-8a93e407635d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_BusinessAcquisitionProFormaEarningsPerShareAbstract_d619bb82-3c88-41f3-a510-23abb4fb7993" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_17367d8e-45b8-40e6-9739-8a93e407635d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/EmployeeBenefitPlansAdditionalInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#EmployeeBenefitPlansAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/EmployeeBenefitPlansAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_92e2b934-cb9e-46d0-8e8d-9f0aeb2a1393" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_92e2b934-cb9e-46d0-8e8d-9f0aeb2a1393" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_fc5346af-b162-43b3-b9c9-98d34fe54744" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_92e2b934-cb9e-46d0-8e8d-9f0aeb2a1393" xlink:to="loc_srt_TitleOfIndividualAxis_fc5346af-b162-43b3-b9c9-98d34fe54744" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_fc5346af-b162-43b3-b9c9-98d34fe54744_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_fc5346af-b162-43b3-b9c9-98d34fe54744" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_fc5346af-b162-43b3-b9c9-98d34fe54744_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_7737f4c6-1fe6-4e32-979d-cedea72cebd9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_fc5346af-b162-43b3-b9c9-98d34fe54744" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_7737f4c6-1fe6-4e32-979d-cedea72cebd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_11e1babd-247c-47fc-91f8-c8e73e8b1d6e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_7737f4c6-1fe6-4e32-979d-cedea72cebd9" xlink:to="loc_srt_DirectorMember_11e1babd-247c-47fc-91f8-c8e73e8b1d6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_0048b8a4-a3dc-4f26-a719-5017df310b12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_92e2b934-cb9e-46d0-8e8d-9f0aeb2a1393" xlink:to="loc_us-gaap_AwardTypeAxis_0048b8a4-a3dc-4f26-a719-5017df310b12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0048b8a4-a3dc-4f26-a719-5017df310b12_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0048b8a4-a3dc-4f26-a719-5017df310b12" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0048b8a4-a3dc-4f26-a719-5017df310b12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e06afa2-e07f-4d6c-8ef3-4971a99aad1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0048b8a4-a3dc-4f26-a719-5017df310b12" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e06afa2-e07f-4d6c-8ef3-4971a99aad1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RestrictedStockUnitsForNonEmployeeDirectorsRsusMember_fdbd6ba0-96d9-40ae-8abb-49795184823c" xlink:href="kai-20260103.xsd#kai_RestrictedStockUnitsForNonEmployeeDirectorsRsusMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e06afa2-e07f-4d6c-8ef3-4971a99aad1f" xlink:to="loc_kai_RestrictedStockUnitsForNonEmployeeDirectorsRsusMember_fdbd6ba0-96d9-40ae-8abb-49795184823c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_PerformanceBasedRestrictedStockUnitsMember_7359d548-801d-4e67-bdfe-5de374550889" xlink:href="kai-20260103.xsd#kai_PerformanceBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e06afa2-e07f-4d6c-8ef3-4971a99aad1f" xlink:to="loc_kai_PerformanceBasedRestrictedStockUnitsMember_7359d548-801d-4e67-bdfe-5de374550889" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_TimeBasedRestrictedStockUnitsMember_4c3b53f1-b233-4bb1-a3a3-8b12c5538de0" xlink:href="kai-20260103.xsd#kai_TimeBasedRestrictedStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e06afa2-e07f-4d6c-8ef3-4971a99aad1f" xlink:to="loc_kai_TimeBasedRestrictedStockUnitsMember_4c3b53f1-b233-4bb1-a3a3-8b12c5538de0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_841237c1-e7d8-4d80-94cd-fbe51eb91421" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e06afa2-e07f-4d6c-8ef3-4971a99aad1f" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_841237c1-e7d8-4d80-94cd-fbe51eb91421" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_EmployeeStockPurchasePlanAwardsMember_2c9c3a96-7fb2-4923-b691-428732da5dc6" xlink:href="kai-20260103.xsd#kai_EmployeeStockPurchasePlanAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4e06afa2-e07f-4d6c-8ef3-4971a99aad1f" xlink:to="loc_kai_EmployeeStockPurchasePlanAwardsMember_2c9c3a96-7fb2-4923-b691-428732da5dc6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_25ef44c7-762f-4898-9342-6341d0c7299c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_25ef44c7-762f-4898-9342-6341d0c7299c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_8aa8b604-11d9-419d-9c8c-172fa5311cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_8aa8b604-11d9-419d-9c8c-172fa5311cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_SharebasedCompensationArrangementbySharebasedPaymentAwardSharesReceivedUponVesting_91f42d1e-e4f5-46fe-a4e0-d8ecd6bad9ce" xlink:href="kai-20260103.xsd#kai_SharebasedCompensationArrangementbySharebasedPaymentAwardSharesReceivedUponVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_kai_SharebasedCompensationArrangementbySharebasedPaymentAwardSharesReceivedUponVesting_91f42d1e-e4f5-46fe-a4e0-d8ecd6bad9ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2adac6d2-45f9-4435-a8c6-b0831dcd3480" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2adac6d2-45f9-4435-a8c6-b0831dcd3480" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_4e30ec98-4d37-4c12-8de2-806a1195ec4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_4e30ec98-4d37-4c12-8de2-806a1195ec4b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_3e9456a3-a544-42ba-974f-73b020edce5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_3e9456a3-a544-42ba-974f-73b020edce5a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_8de479d8-4756-4412-80bf-628632bbc74d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_8de479d8-4756-4412-80bf-628632bbc74d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_dbb10412-45ba-40f6-94c2-1b33a74232ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_dbb10412-45ba-40f6-94c2-1b33a74232ab" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_994cf0b2-1266-4671-a306-8bf11fbf8ae8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_994cf0b2-1266-4671-a306-8bf11fbf8ae8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_EmployeeStockOwnershipPlanEsopDiscountToMarket_796f0ea8-9706-406b-b615-fb3959b7490e" xlink:href="kai-20260103.xsd#kai_EmployeeStockOwnershipPlanEsopDiscountToMarket"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_kai_EmployeeStockOwnershipPlanEsopDiscountToMarket_796f0ea8-9706-406b-b615-fb3959b7490e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_EmployeeStockPurchasePlanEsppPeriodOfRestrictionOnResaleMaximum_383d717f-1c48-4063-942c-4b4cae7860f6" xlink:href="kai-20260103.xsd#kai_EmployeeStockPurchasePlanEsppPeriodOfRestrictionOnResaleMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_kai_EmployeeStockPurchasePlanEsppPeriodOfRestrictionOnResaleMaximum_383d717f-1c48-4063-942c-4b4cae7860f6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_e45a7679-a805-498c-b1f7-73adb2f8e9f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_e45a7679-a805-498c-b1f7-73adb2f8e9f5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_a5481a93-e844-43a4-9155-80a0e4c2a75d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_a5481a93-e844-43a4-9155-80a0e4c2a75d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_73e22dae-279f-41c2-b690-28e682d73b57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_cf4c3e07-02b5-49f0-82a4-3db594438f28" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_73e22dae-279f-41c2-b690-28e682d73b57" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/EmployeeBenefitPlansComponentsStockBasedCompensationExpenseDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#EmployeeBenefitPlansComponentsStockBasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/EmployeeBenefitPlansComponentsStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a1490b35-57f2-46cb-8e44-78aafe3d86d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7ec49435-33ec-456b-811a-5a7c5e1a7f8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a1490b35-57f2-46cb-8e44-78aafe3d86d3" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7ec49435-33ec-456b-811a-5a7c5e1a7f8e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_008148ef-5e32-43fa-a36d-90edb28a5286" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7ec49435-33ec-456b-811a-5a7c5e1a7f8e" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_008148ef-5e32-43fa-a36d-90edb28a5286" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_008148ef-5e32-43fa-a36d-90edb28a5286_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_008148ef-5e32-43fa-a36d-90edb28a5286" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_008148ef-5e32-43fa-a36d-90edb28a5286_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1f15fe08-0a9f-4b6c-8b49-9e050fd226f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_008148ef-5e32-43fa-a36d-90edb28a5286" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1f15fe08-0a9f-4b6c-8b49-9e050fd226f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_287f0daf-e6fc-4b07-9057-7e51479e5fce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1f15fe08-0a9f-4b6c-8b49-9e050fd226f4" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_287f0daf-e6fc-4b07-9057-7e51479e5fce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_9c49d046-dd92-486e-8997-0289c326db3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7ec49435-33ec-456b-811a-5a7c5e1a7f8e" xlink:to="loc_us-gaap_AwardTypeAxis_9c49d046-dd92-486e-8997-0289c326db3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9c49d046-dd92-486e-8997-0289c326db3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_9c49d046-dd92-486e-8997-0289c326db3c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_9c49d046-dd92-486e-8997-0289c326db3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7fd18004-d4cd-4b19-8f32-e6bf53b3ca4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_9c49d046-dd92-486e-8997-0289c326db3c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7fd18004-d4cd-4b19-8f32-e6bf53b3ca4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_3e19c25e-d3a8-42cc-a0bd-b04305465c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7fd18004-d4cd-4b19-8f32-e6bf53b3ca4e" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_3e19c25e-d3a8-42cc-a0bd-b04305465c6a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_EmployeeStockPurchasePlanAwardsMember_2fc55c42-a297-4f98-b681-1cf7b06881ad" xlink:href="kai-20260103.xsd#kai_EmployeeStockPurchasePlanAwardsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7fd18004-d4cd-4b19-8f32-e6bf53b3ca4e" xlink:to="loc_kai_EmployeeStockPurchasePlanAwardsMember_2fc55c42-a297-4f98-b681-1cf7b06881ad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_332b1fc1-edfd-4a1e-99b0-1678bc41a36f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a1490b35-57f2-46cb-8e44-78aafe3d86d3" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_332b1fc1-edfd-4a1e-99b0-1678bc41a36f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/EmployeeBenefitPlansActivityoftheUnvestedRSUsDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#EmployeeBenefitPlansActivityoftheUnvestedRSUsDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/EmployeeBenefitPlansActivityoftheUnvestedRSUsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1444b4f1-5877-45e9-b168-a4592c68c5ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cd66e41f-787e-4e87-b771-fd93e7c7c272" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1444b4f1-5877-45e9-b168-a4592c68c5ff" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cd66e41f-787e-4e87-b771-fd93e7c7c272" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_13a7d39c-facf-4060-a3f0-b94a47b2a1dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_cd66e41f-787e-4e87-b771-fd93e7c7c272" xlink:to="loc_us-gaap_AwardTypeAxis_13a7d39c-facf-4060-a3f0-b94a47b2a1dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_13a7d39c-facf-4060-a3f0-b94a47b2a1dd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_13a7d39c-facf-4060-a3f0-b94a47b2a1dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_13a7d39c-facf-4060-a3f0-b94a47b2a1dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7f3a3d07-7e1b-4c6e-88e9-218eedda64f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_13a7d39c-facf-4060-a3f0-b94a47b2a1dd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7f3a3d07-7e1b-4c6e-88e9-218eedda64f4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_4e45c526-1b9f-41d3-ac75-59ca6a716ee9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_7f3a3d07-7e1b-4c6e-88e9-218eedda64f4" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_4e45c526-1b9f-41d3-ac75-59ca6a716ee9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dbb33a75-7c82-471c-a205-857ab167fe74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1444b4f1-5877-45e9-b168-a4592c68c5ff" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dbb33a75-7c82-471c-a205-857ab167fe74" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1bb50a4d-bf8d-438a-be9f-f7d5d083726e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dbb33a75-7c82-471c-a205-857ab167fe74" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_1bb50a4d-bf8d-438a-be9f-f7d5d083726e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_d59c646d-70ab-4981-ab62-e18c400e205f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dbb33a75-7c82-471c-a205-857ab167fe74" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_d59c646d-70ab-4981-ab62-e18c400e205f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_094e00f7-939b-487c-ae7d-3eb232a09696" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dbb33a75-7c82-471c-a205-857ab167fe74" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_094e00f7-939b-487c-ae7d-3eb232a09696" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_371f2564-3d31-44c3-87fb-8eab2c9afbac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_dbb33a75-7c82-471c-a205-857ab167fe74" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_371f2564-3d31-44c3-87fb-8eab2c9afbac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_3e1b72ed-c096-4a89-8358-3bb7036c8132" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_cf4fbf9e-d4c5-402b-b50f-b2e6b431b3da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1444b4f1-5877-45e9-b168-a4592c68c5ff" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_cf4fbf9e-d4c5-402b-b50f-b2e6b431b3da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8df06654-ee91-4bd0-9370-3a276c113f8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_cf4fbf9e-d4c5-402b-b50f-b2e6b431b3da" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8df06654-ee91-4bd0-9370-3a276c113f8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_32c0ace4-988d-4b59-abd6-b7b9ac938f04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_cf4fbf9e-d4c5-402b-b50f-b2e6b431b3da" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_32c0ace4-988d-4b59-abd6-b7b9ac938f04" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_1b6dc39c-ac3e-4c4f-975e-e0500e902a4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_cf4fbf9e-d4c5-402b-b50f-b2e6b431b3da" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_1b6dc39c-ac3e-4c4f-975e-e0500e902a4f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_facd9d58-51d0-4ddc-93e0-9b780de99a29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_cf4fbf9e-d4c5-402b-b50f-b2e6b431b3da" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_facd9d58-51d0-4ddc-93e0-9b780de99a29" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_0d088286-ae88-40b8-aafe-055d8d588deb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#IncomeTaxesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_7657fbb9-2e53-4222-9928-f08e7aabe272" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_7657fbb9-2e53-4222-9928-f08e7aabe272" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_0e62beb8-c5f7-45b6-a93e-b730b54379d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_7657fbb9-2e53-4222-9928-f08e7aabe272" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_0e62beb8-c5f7-45b6-a93e-b730b54379d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_0e62beb8-c5f7-45b6-a93e-b730b54379d1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_0e62beb8-c5f7-45b6-a93e-b730b54379d1" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_0e62beb8-c5f7-45b6-a93e-b730b54379d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_5462a122-6546-4d0d-ae2e-26c6b361c864" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_0e62beb8-c5f7-45b6-a93e-b730b54379d1" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_5462a122-6546-4d0d-ae2e-26c6b361c864" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember_75a2257d-cfa0-416b-91e2-b0889a8b39e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternalRevenueServiceIRSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_5462a122-6546-4d0d-ae2e-26c6b361c864" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember_75a2257d-cfa0-416b-91e2-b0889a8b39e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_86baebde-6e6e-4cd1-83cc-6dc9fa1f9dc1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_5462a122-6546-4d0d-ae2e-26c6b361c864" xlink:to="loc_us-gaap_ForeignCountryMember_86baebde-6e6e-4cd1-83cc-6dc9fa1f9dc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_019c9394-85bf-70bd-a8d7-5fcadfaffb9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_5462a122-6546-4d0d-ae2e-26c6b361c864" xlink:to="loc_us-gaap_DomesticCountryMember_019c9394-85bf-70bd-a8d7-5fcadfaffb9d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_4ef912af-3504-495b-a5ea-e3da701e61bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_019c9394-85bf-70bd-a8d7-5fcadfaffb9d" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_4ef912af-3504-495b-a5ea-e3da701e61bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019caebd-ad96-7720-8692-a399ca7288b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_7657fbb9-2e53-4222-9928-f08e7aabe272" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019caebd-ad96-7720-8692-a399ca7288b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019caebd-ad96-7720-8692-a399ca7288b1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019caebd-ad96-7720-8692-a399ca7288b1" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019caebd-ad96-7720-8692-a399ca7288b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019caebd-ad96-705a-8ef3-546b2f011449" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019caebd-ad96-7720-8692-a399ca7288b1" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019caebd-ad96-705a-8ef3-546b2f011449" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ClydeIndustriesMember_019caebd-cf78-7760-839d-acd33e3059e5" xlink:href="kai-20260103.xsd#kai_ClydeIndustriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019caebd-ad96-705a-8ef3-546b2f011449" xlink:to="loc_kai_ClydeIndustriesMember_019caebd-cf78-7760-839d-acd33e3059e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_019c93a6-39c8-7446-a43d-de9007d1edd3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_019c93a6-39c8-7446-a43d-de9007d1edd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_019c93a7-13ea-72fb-9d65-6aed9a2ef633" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_019c93a7-13ea-72fb-9d65-6aed9a2ef633" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_019c93a7-13ea-7403-b6bc-97657da7f50e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_019c93a7-13ea-7403-b6bc-97657da7f50e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_019c93a7-13ea-7e96-83d6-95134cc9ccf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_OperatingLossCarryforwards_019c93a7-13ea-7e96-83d6-95134cc9ccf0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_019c93a7-13ea-76aa-b5f8-2b7a1d3dd6f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_019c93a7-13ea-76aa-b5f8-2b7a1d3dd6f8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_019c93a7-13ea-7e22-bc7f-8cd34d537296" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_019c93a7-13ea-7e22-bc7f-8cd34d537296" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_019c93a7-13ea-78f0-af6a-e606d3590da9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_019c93a7-13ea-78f0-af6a-e606d3590da9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsOfForeignSubsidiaries_019c93a7-4fc4-7d22-a78f-4945ae947754" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UndistributedEarningsOfForeignSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_UndistributedEarningsOfForeignSubsidiaries_019c93a7-4fc4-7d22-a78f-4945ae947754" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_IncomeTaxExpenseBenefitEstimatedRepatriation_019c93a7-4fc4-7d37-9936-9e732744ffb8" xlink:href="kai-20260103.xsd#kai_IncomeTaxExpenseBenefitEstimatedRepatriation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_kai_IncomeTaxExpenseBenefitEstimatedRepatriation_019c93a7-4fc4-7d37-9936-9e732744ffb8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_UndistributedEarningsofForeignSubsidiariesExcludingThoseRepatriatedBackDomestically_019c93a7-4fc4-787e-b94b-f212402dbafb" xlink:href="kai-20260103.xsd#kai_UndistributedEarningsofForeignSubsidiariesExcludingThoseRepatriatedBackDomestically"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_kai_UndistributedEarningsofForeignSubsidiariesExcludingThoseRepatriatedBackDomestically_019c93a7-4fc4-787e-b94b-f212402dbafb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_EstimatedWithholdingLiabilityRelatedToUndistributedEarningsOfForeignSubsidiaries_019c93a7-4fc4-77aa-ad57-580a7c139636" xlink:href="kai-20260103.xsd#kai_EstimatedWithholdingLiabilityRelatedToUndistributedEarningsOfForeignSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_kai_EstimatedWithholdingLiabilityRelatedToUndistributedEarningsOfForeignSubsidiaries_019c93a7-4fc4-77aa-ad57-580a7c139636" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_019c93a7-4fc4-7b23-a1f3-072bdf59be1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_019c93a7-4fc4-7b23-a1f3-072bdf59be1a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_019c93a7-4fc4-7f42-8465-f1b8222b7e3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_019c93a7-4fc4-7f42-8465-f1b8222b7e3d" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_019c93a7-9f67-76b4-bf19-9cdcb12ded49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_019c93a7-9f67-76b4-bf19-9cdcb12ded49" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_019c93a7-9f67-7f5a-a52d-023724924138" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_dd2cb02b-5127-46c2-8a61-4b4e5879172e" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_019c93a7-9f67-7f5a-a52d-023724924138" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/IncomeTaxesEffectiveTaxRateReconciliationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#IncomeTaxesEffectiveTaxRateReconciliationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/IncomeTaxesEffectiveTaxRateReconciliationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019bb2ac-9036-7ee4-a0cf-9aa491fb5026" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019bb2ac-9036-755b-ae0c-bb76c6d70301" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019bb2ac-9036-7ee4-a0cf-9aa491fb5026" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019bb2ac-9036-755b-ae0c-bb76c6d70301" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2ac-9036-7b40-9fde-63f3cc1b0c94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019bb2ac-9036-755b-ae0c-bb76c6d70301" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2ac-9036-7b40-9fde-63f3cc1b0c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2ac-9036-7b40-9fde-63f3cc1b0c94_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2ac-9036-7b40-9fde-63f3cc1b0c94" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2ac-9036-7b40-9fde-63f3cc1b0c94_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2ac-9036-7342-a404-7481e6a8309e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2ac-9036-7b40-9fde-63f3cc1b0c94" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2ac-9036-7342-a404-7481e6a8309e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_019bb2ac-9036-7568-a946-221954b8ad0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2ac-9036-7342-a404-7481e6a8309e" xlink:to="loc_us-gaap_ForeignCountryMember_019bb2ac-9036-7568-a946-221954b8ad0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_019bb2b1-cf30-76e5-883a-e0caa9c40bbe" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019bb2ac-9036-7568-a946-221954b8ad0c" xlink:to="loc_country_CA_019bb2b1-cf30-76e5-883a-e0caa9c40bbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_019c6a96-5349-7337-81d0-942b7e15749f" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019bb2ac-9036-7568-a946-221954b8ad0c" xlink:to="loc_country_CN_019c6a96-5349-7337-81d0-942b7e15749f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019bb2ac-9036-73e7-b489-41355996e55f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019bb2ac-9036-7568-a946-221954b8ad0c" xlink:to="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019bb2ac-9036-73e7-b489-41355996e55f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_019bb2ac-9036-7da4-95c2-7060063acf4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2ac-9036-7342-a404-7481e6a8309e" xlink:to="loc_us-gaap_DomesticCountryMember_019bb2ac-9036-7da4-95c2-7060063acf4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019bb2ac-9036-7c78-894f-c948a36a9765" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_019bb2ac-9036-7da4-95c2-7060063acf4b" xlink:to="loc_country_US_019bb2ac-9036-7c78-894f-c948a36a9765" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019bb2ac-9036-7ee4-a0cf-9aa491fb5026" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_019bb2b3-21ce-7638-807d-6423f82f8db6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_019bb2b3-21ce-7638-807d-6423f82f8db6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_019bb2b3-21ce-7d08-9509-295d2895ecf1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_019bb2b3-21ce-7d08-9509-295d2895ecf1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_019bb2b3-21ce-7973-a9c9-59475b637406" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_019bb2b3-21ce-7973-a9c9-59475b637406" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_019bb2b3-21ce-7af6-8d7b-4fdeccd70d02" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseShareBasedCompensationCost_019bb2b3-21ce-7af6-8d7b-4fdeccd70d02" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_019bb2b3-21ce-739a-8296-a4d687314128" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments_019bb2b3-21ce-739a-8296-a4d687314128" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderOtherAmount_019bb2b3-21ce-72a9-ae7a-03a74294c3ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderOtherAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderOtherAmount_019bb2b3-21ce-72a9-ae7a-03a74294c3ad" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsForeign_019c9383-28fd-7e0b-a342-1116abc295bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsForeign_019c9383-28fd-7e0b-a342-1116abc295bb" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxCreditsOther_019bb2b3-21ce-7f92-bfdb-54c5e5c8e9ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationTaxCreditsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxCreditsOther_019bb2b3-21ce-7f92-bfdb-54c5e5c8e9ce" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_019c56c1-a4c6-7e2f-abdb-8686b08dfa2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_019c56c1-a4c6-7e2f-abdb-8686b08dfa2e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther_019bb2b3-21ce-7800-94e0-514313bc42e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseOther_019bb2b3-21ce-7800-94e0-514313bc42e6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxContingencies_019bb2b3-21ce-72f5-b447-1c2494ecd088" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxReconciliationTaxContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxReconciliationTaxContingencies_019bb2b3-21ce-72f5-b447-1c2494ecd088" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019bb2ac-9036-7a33-b61d-ecffe06f2791" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsIncomeTaxReconciliationAbstract_019bb2ac-9036-7fd7-b2e6-8e07b5466c1b" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019bb2ac-9036-7a33-b61d-ecffe06f2791" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019bb2ac-9036-7ee4-a0cf-9aa491fb5026" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_019bb2b5-9497-7463-a0b7-ba7a042681f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_019bb2b5-9497-7463-a0b7-ba7a042681f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_019bb2b5-9497-7bc7-a57b-56c45b0d3a33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes_019bb2b5-9497-7bc7-a57b-56c45b0d3a33" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential_019bb2b5-9497-7a29-9498-7fa4cb529c22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationForeignIncomeTaxRateDifferential_019bb2b5-9497-7a29-9498-7fa4cb529c22" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_019bb2b5-9497-7953-8dde-ade04c6b5141" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseShareBasedCompensationCost_019bb2b5-9497-7953-8dde-ade04c6b5141" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_019bb2b5-9497-7f9a-be0c-41e86b5b386c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationOtherAdjustments_019bb2b5-9497-7f9a-be0c-41e86b5b386c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderOtherPercent_019bb2b5-9497-790a-83fd-50bf10094b06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderOtherPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationCrossBorderOtherPercent_019bb2b5-9497-790a-83fd-50bf10094b06" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsForeign_019c9383-4b53-728c-8475-035d15245c34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsForeign"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsForeign_019c9383-4b53-728c-8475-035d15245c34" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther_019bb2b5-9497-7fb5-a484-f4b5256cad22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxCreditsOther_019bb2b5-9497-7fb5-a484-f4b5256cad22" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_019c56c2-0ddb-7d7e-b1b8-8f27731b7849" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationChangeInDeferredTaxAssetsValuationAllowance_019c56c2-0ddb-7d7e-b1b8-8f27731b7849" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther_019bb2b5-9497-79c1-aedc-c9ae2827e06f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseOther_019bb2b5-9497-79c1-aedc-c9ae2827e06f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_019bb2b5-9497-74dc-ba67-d7fd53dda8b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTaxContingencies_019bb2b5-9497-74dc-ba67-d7fd53dda8b2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019bb2ac-9036-7ab0-bcf8-94c7c24835ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperationsTaxRateReconciliationAbstract_019bb2ac-9036-7371-b34f-3f2a34e4862f" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019bb2ac-9036-7ab0-bcf8-94c7c24835ad" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/IncomeTaxesSupplementalCashFlowInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#IncomeTaxesSupplementalCashFlowInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/IncomeTaxesSupplementalCashFlowInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019bb2c2-c1b0-7c69-bfb2-85a723bf9b2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionTable_019bb2c2-867b-759e-b128-4705ba2a92a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidByIndividualJurisdictionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019bb2c2-c1b0-7c69-bfb2-85a723bf9b2b" xlink:to="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionTable_019bb2c2-867b-759e-b128-4705ba2a92a7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2c3-1ab6-7cc3-a8e7-556f27db3d8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionTable_019bb2c2-867b-759e-b128-4705ba2a92a7" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2c3-1ab6-7cc3-a8e7-556f27db3d8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2c3-1ab6-7cc3-a8e7-556f27db3d8f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2c3-1ab6-7cc3-a8e7-556f27db3d8f" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2c3-1ab6-7cc3-a8e7-556f27db3d8f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2c3-1ab6-7a1b-8057-322231ee306e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019bb2c3-1ab6-7cc3-a8e7-556f27db3d8f" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2c3-1ab6-7a1b-8057-322231ee306e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_019c9582-2ce7-7215-a4bf-291de1999de9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019bb2c3-1ab6-7a1b-8057-322231ee306e" xlink:to="loc_us-gaap_ForeignCountryMember_019c9582-2ce7-7215-a4bf-291de1999de9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_BR_019bb2c3-1ab6-7bfa-9d49-775b6f05c715" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_BR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019c9582-2ce7-7215-a4bf-291de1999de9" xlink:to="loc_country_BR_019bb2c3-1ab6-7bfa-9d49-775b6f05c715" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_019bb2c3-1ab6-72cb-9337-e730b9e740bb" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019c9582-2ce7-7215-a4bf-291de1999de9" xlink:to="loc_country_CA_019bb2c3-1ab6-72cb-9337-e730b9e740bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_019bb2c3-1ab6-7d9c-8537-953411b2852c" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019c9582-2ce7-7215-a4bf-291de1999de9" xlink:to="loc_country_CN_019bb2c3-1ab6-7d9c-8537-953411b2852c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_FI_019c9389-f5d4-7442-b289-aa48518e1624" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_FI"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019c9582-2ce7-7215-a4bf-291de1999de9" xlink:to="loc_country_FI_019c9389-f5d4-7442-b289-aa48518e1624" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019bb2c3-1ab6-7b4b-a8f4-bec6d39d78e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ForeignCountryMember_019c9582-2ce7-7215-a4bf-291de1999de9" xlink:to="loc_us-gaap_ForeignTaxJurisdictionOtherMember_019bb2c3-1ab6-7b4b-a8f4-bec6d39d78e6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019bb2c1-6e26-741e-a91d-f5ed4ad64865" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidFederalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019bb2c2-c1b0-7c69-bfb2-85a723bf9b2b" xlink:to="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019bb2c1-6e26-741e-a91d-f5ed4ad64865" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019bb2c1-6e26-7597-a38c-4a3f8f327997" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019bb2c2-c1b0-7c69-bfb2-85a723bf9b2b" xlink:to="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019bb2c1-6e26-7597-a38c-4a3f8f327997" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidForeignAfterRefundReceived_019bb2c1-6e26-7f62-9a4b-12cb33484481" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidForeignAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019bb2c2-c1b0-7c69-bfb2-85a723bf9b2b" xlink:to="loc_us-gaap_IncomeTaxPaidForeignAfterRefundReceived_019bb2c1-6e26-7f62-9a4b-12cb33484481" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_019bb2c1-6e26-7fde-9946-a540c3297855" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019bb2c2-c1b0-7c69-bfb2-85a723bf9b2b" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_019bb2c1-6e26-7fde-9946-a540c3297855" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/LongTermObligationsScheduleofLongtermObligationsDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#LongTermObligationsScheduleofLongtermObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/LongTermObligationsScheduleofLongtermObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_266b71b6-6fce-4e01-a036-7e47078fd9d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:to="loc_us-gaap_DebtInstrumentTable_266b71b6-6fce-4e01-a036-7e47078fd9d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_ea7d7dd6-914e-48ec-9bf4-60be08d5dc19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_266b71b6-6fce-4e01-a036-7e47078fd9d1" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_ea7d7dd6-914e-48ec-9bf4-60be08d5dc19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_ea7d7dd6-914e-48ec-9bf4-60be08d5dc19_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ea7d7dd6-914e-48ec-9bf4-60be08d5dc19" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_ea7d7dd6-914e-48ec-9bf4-60be08d5dc19_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_e48a2432-ae1d-48ba-9e12-6815faf18bc3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_ea7d7dd6-914e-48ec-9bf4-60be08d5dc19" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_e48a2432-ae1d-48ba-9e12-6815faf18bc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_91eaaf5e-3dd1-458c-b1cb-2dcaaa18a0ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_e48a2432-ae1d-48ba-9e12-6815faf18bc3" xlink:to="loc_us-gaap_LineOfCreditMember_91eaaf5e-3dd1-458c-b1cb-2dcaaa18a0ce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_800022b9-6baa-4097-b384-393370b4ba84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_e48a2432-ae1d-48ba-9e12-6815faf18bc3" xlink:to="loc_us-gaap_SeniorNotesMember_800022b9-6baa-4097-b384-393370b4ba84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_OtherBorrowingsMember_7723e30d-2cba-491d-a7d5-a4356ede8cc4" xlink:href="kai-20260103.xsd#kai_OtherBorrowingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_e48a2432-ae1d-48ba-9e12-6815faf18bc3" xlink:to="loc_kai_OtherBorrowingsMember_7723e30d-2cba-491d-a7d5-a4356ede8cc4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_36fcb0c4-517e-4333-b715-24f4cdf7abec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:to="loc_us-gaap_LongTermDebt_36fcb0c4-517e-4333-b715-24f4cdf7abec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_f0391d43-d7c2-40c0-9f44-9af06b4918f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:to="loc_us-gaap_FinanceLeaseLiability_f0391d43-d7c2-40c0-9f44-9af06b4918f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherBorrowings_725d6c44-19fb-43dc-9678-48dd6531ea11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:to="loc_us-gaap_OtherBorrowings_725d6c44-19fb-43dc-9678-48dd6531ea11" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities_b32c643e-b762-48b7-895e-d4d7fc53ae8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities_b32c643e-b762-48b7-895e-d4d7fc53ae8b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_f76a0f82-26c1-4e54-acf0-e03295620582" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:to="loc_us-gaap_DebtCurrent_f76a0f82-26c1-4e54-acf0-e03295620582" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_e80e0f9f-0744-401a-9232-e730614e3fc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_311ea19d-aa19-4721-971f-3f9e5d63f65c" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_e80e0f9f-0744-401a-9232-e730614e3fc7" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/LongTermObligationsAdditionalInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#LongTermObligationsAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/LongTermObligationsAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019b8275-1bd5-7780-8e8c-075a2113a029" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:to="loc_us-gaap_DebtInstrumentAxis_019b8275-1bd5-7780-8e8c-075a2113a029" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7780-8e8c-075a2113a029_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b8275-1bd5-7780-8e8c-075a2113a029" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7780-8e8c-075a2113a029_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7e65-97bb-f746cca8e468" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b8275-1bd5-7780-8e8c-075a2113a029" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7e65-97bb-f746cca8e468" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_AmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityCreditAgreementMember_019b8275-1bd5-7573-8661-dd8aa198255f" xlink:href="kai-20260103.xsd#kai_AmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7e65-97bb-f746cca8e468" xlink:to="loc_kai_AmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityCreditAgreementMember_019b8275-1bd5-7573-8661-dd8aa198255f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_EighthAmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityCreditAgreementMember_019b8275-45a6-7b85-a6c8-e3c3f1ca037c" xlink:href="kai-20260103.xsd#kai_EighthAmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7e65-97bb-f746cca8e468" xlink:to="loc_kai_EighthAmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityCreditAgreementMember_019b8275-45a6-7b85-a6c8-e3c3f1ca037c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_NotePurchaseAgreementMember_019b8275-61bc-7390-91df-15a8aff95f7d" xlink:href="kai-20260103.xsd#kai_NotePurchaseAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7e65-97bb-f746cca8e468" xlink:to="loc_kai_NotePurchaseAgreementMember_019b8275-61bc-7390-91df-15a8aff95f7d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_AmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityEuroDenominatedBorrowingMember_019bb2cb-f194-7cac-87f5-f7df1f1cbc02" xlink:href="kai-20260103.xsd#kai_AmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityEuroDenominatedBorrowingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b8275-1bd5-7e65-97bb-f746cca8e468" xlink:to="loc_kai_AmendmentToUnsecuredMultiCurrencyRevolvingCreditFacilityEuroDenominatedBorrowingMember_019bb2cb-f194-7cac-87f5-f7df1f1cbc02" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019b8275-45a6-73ff-811d-b22083fb19b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019b8275-45a6-73ff-811d-b22083fb19b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b8275-45a6-73ff-811d-b22083fb19b9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b8275-45a6-73ff-811d-b22083fb19b9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b8275-45a6-73ff-811d-b22083fb19b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b8275-45a6-723a-88b1-cf2d6c2ce594" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b8275-45a6-73ff-811d-b22083fb19b9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b8275-45a6-723a-88b1-cf2d6c2ce594" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019b8275-45a6-7c51-8a65-8c789d3167c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b8275-45a6-723a-88b1-cf2d6c2ce594" xlink:to="loc_us-gaap_LineOfCreditMember_019b8275-45a6-7c51-8a65-8c789d3167c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019b8275-61bc-7983-8857-421841de737e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b8275-45a6-723a-88b1-cf2d6c2ce594" xlink:to="loc_us-gaap_SeniorNotesMember_019b8275-61bc-7983-8857-421841de737e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_OtherBorrowingsMember_019cac51-43a9-7f93-9ebd-0bfa417de280" xlink:href="kai-20260103.xsd#kai_OtherBorrowingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b8275-45a6-723a-88b1-cf2d6c2ce594" xlink:to="loc_kai_OtherBorrowingsMember_019cac51-43a9-7f93-9ebd-0bfa417de280" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019b8275-45a6-756f-b576-68b93c51f068" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:to="loc_srt_RangeAxis_019b8275-45a6-756f-b576-68b93c51f068" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019b8275-45a6-756f-b576-68b93c51f068_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019b8275-45a6-756f-b576-68b93c51f068" xlink:to="loc_srt_RangeMember_019b8275-45a6-756f-b576-68b93c51f068_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019b8275-45a6-7fbf-8f93-47aac13311e0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019b8275-45a6-756f-b576-68b93c51f068" xlink:to="loc_srt_RangeMember_019b8275-45a6-7fbf-8f93-47aac13311e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019b8275-45a6-7753-8d63-553e2471ae7a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019b8275-45a6-7fbf-8f93-47aac13311e0" xlink:to="loc_srt_MinimumMember_019b8275-45a6-7753-8d63-553e2471ae7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019b8275-45a6-767e-b345-0039a9542874" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019b8275-45a6-7fbf-8f93-47aac13311e0" xlink:to="loc_srt_MaximumMember_019b8275-45a6-767e-b345-0039a9542874" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_019b8275-45a6-7d20-91fb-1a7c6c91d408" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:to="loc_us-gaap_VariableRateAxis_019b8275-45a6-7d20-91fb-1a7c6c91d408" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019b8275-45a6-7d20-91fb-1a7c6c91d408_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_019b8275-45a6-7d20-91fb-1a7c6c91d408" xlink:to="loc_us-gaap_VariableRateDomain_019b8275-45a6-7d20-91fb-1a7c6c91d408_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_019b8275-45a6-7642-a0b6-b8bb921a15f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_019b8275-45a6-7d20-91fb-1a7c6c91d408" xlink:to="loc_us-gaap_VariableRateDomain_019b8275-45a6-7642-a0b6-b8bb921a15f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_019b8275-45a6-7a26-b441-149ab7afbca4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019b8275-45a6-7642-a0b6-b8bb921a15f8" xlink:to="loc_us-gaap_BaseRateMember_019b8275-45a6-7a26-b441-149ab7afbca4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_EurocurrencyRateTermSOFRTermCORRAAndRFRMember_019b8275-45a6-7c88-b4b9-65d7101fbad0" xlink:href="kai-20260103.xsd#kai_EurocurrencyRateTermSOFRTermCORRAAndRFRMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_019b8275-45a6-7642-a0b6-b8bb921a15f8" xlink:to="loc_kai_EurocurrencyRateTermSOFRTermCORRAAndRFRMember_019b8275-45a6-7c88-b4b9-65d7101fbad0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019b8275-45a6-7b10-8256-db445f39bbb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:to="loc_us-gaap_CreditFacilityAxis_019b8275-45a6-7b10-8256-db445f39bbb1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019b8275-45a6-7b10-8256-db445f39bbb1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019b8275-45a6-7b10-8256-db445f39bbb1" xlink:to="loc_us-gaap_CreditFacilityDomain_019b8275-45a6-7b10-8256-db445f39bbb1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019b8275-45a6-7820-90a9-165829c8e33c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019b8275-45a6-7b10-8256-db445f39bbb1" xlink:to="loc_us-gaap_CreditFacilityDomain_019b8275-45a6-7820-90a9-165829c8e33c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019b8275-45a6-7dfc-8fb1-70d1d8e36a1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019b8275-45a6-7820-90a9-165829c8e33c" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019b8275-45a6-7dfc-8fb1-70d1d8e36a1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019b8275-61bc-7267-b22a-ee1c0ecae7b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_26234edd-33c0-42a2-ad5e-c72611c83dcd" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019b8275-61bc-7267-b22a-ee1c0ecae7b4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8275-61bc-7267-b22a-ee1c0ecae7b4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019b8275-61bc-7267-b22a-ee1c0ecae7b4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8275-61bc-7267-b22a-ee1c0ecae7b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8275-61bc-72bd-8dbe-840a964b18d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019b8275-61bc-7267-b22a-ee1c0ecae7b4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8275-61bc-72bd-8dbe-840a964b18d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_TheClouthGroupOfCompaniesMember_019b8275-61bc-7c46-baf6-e74902988738" xlink:href="kai-20260103.xsd#kai_TheClouthGroupOfCompaniesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8275-61bc-72bd-8dbe-840a964b18d7" xlink:to="loc_kai_TheClouthGroupOfCompaniesMember_019b8275-61bc-7c46-baf6-e74902988738" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019b8275-1bd5-785d-b84e-5120cc831e00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_019b8275-1bd5-785d-b84e-5120cc831e00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_LineOfCreditFacilityAdditionalBorrowingCapacity_019b8275-45a6-74ba-82ef-b2f55a4e1935" xlink:href="kai-20260103.xsd#kai_LineOfCreditFacilityAdditionalBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_kai_LineOfCreditFacilityAdditionalBorrowingCapacity_019b8275-45a6-74ba-82ef-b2f55a4e1935" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019b8275-45a6-75ad-94e4-700e5de5071f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_019b8275-45a6-75ad-94e4-700e5de5071f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_LineOfCreditFacilityMaximumUnrestrictedCash_019b8275-45a6-7c2c-b484-b6bce4f270f5" xlink:href="kai-20260103.xsd#kai_LineOfCreditFacilityMaximumUnrestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_kai_LineOfCreditFacilityMaximumUnrestrictedCash_019b8275-45a6-7c2c-b484-b6bce4f270f5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_019b8275-45a6-7d60-a1d2-d0e575e14e40" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_019b8275-45a6-7d60-a1d2-d0e575e14e40" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_MaximumConsolidatedLeverageRatio_019b8275-45a6-7e83-8c59-2a68b0ad469c" xlink:href="kai-20260103.xsd#kai_MaximumConsolidatedLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_kai_MaximumConsolidatedLeverageRatio_019b8275-45a6-7e83-8c59-2a68b0ad469c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_MaximumConsolidatedLeverageRatioUponMaterialAcquisition_019b8275-45a6-77ef-b06d-b7c1b2095aa7" xlink:href="kai-20260103.xsd#kai_MaximumConsolidatedLeverageRatioUponMaterialAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_kai_MaximumConsolidatedLeverageRatioUponMaterialAcquisition_019b8275-45a6-77ef-b06d-b7c1b2095aa7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019b8275-61bc-7e57-ae0f-5849928aa671" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_LongTermDebt_019b8275-61bc-7e57-ae0f-5849928aa671" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019bb2cb-f194-76f2-b23c-d91912d11beb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019bb2cb-f194-76f2-b23c-d91912d11beb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtWeightedAverageInterestRate_019b8275-45a6-73df-bbfb-dbd122d5dba0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_LongtermDebtWeightedAverageInterestRate_019b8275-45a6-73df-bbfb-dbd122d5dba0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_019b8275-45a6-7012-bb00-a54f46bcea3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_019b8275-45a6-7012-bb00-a54f46bcea3d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019b8275-61bc-74ba-b2e5-727185b6aa2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019b8275-61bc-74ba-b2e5-727185b6aa2d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019b8275-61bc-7183-b1a4-8e9017cc2b7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019b8275-61bc-7183-b1a4-8e9017cc2b7a" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019b8275-61bc-7c94-8c8e-e881a463e3d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_019b8275-61bc-7c94-8c8e-e881a463e3d4" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherBorrowings_019cac51-43a9-7f43-9a44-cf7e9fcba142" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b8275-1bd5-7c88-8417-4d188179bc86" xlink:to="loc_us-gaap_OtherBorrowings_019cac51-43a9-7f43-9a44-cf7e9fcba142" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/CommitmentsandContingenciesLettersofCreditandBankGuaranteesDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#CommitmentsandContingenciesLettersofCreditandBankGuaranteesDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/CommitmentsandContingenciesLettersofCreditandBankGuaranteesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_95431783-1df0-4631-ae5f-db15146a003c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_36d57d1b-052d-4c1a-b97c-9a22305ec76f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_95431783-1df0-4631-ae5f-db15146a003c" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_36d57d1b-052d-4c1a-b97c-9a22305ec76f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_665edb6a-66f5-4b67-9ade-66df36e590fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_36d57d1b-052d-4c1a-b97c-9a22305ec76f" xlink:to="loc_us-gaap_CreditFacilityAxis_665edb6a-66f5-4b67-9ade-66df36e590fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_665edb6a-66f5-4b67-9ade-66df36e590fb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_665edb6a-66f5-4b67-9ade-66df36e590fb" xlink:to="loc_us-gaap_CreditFacilityDomain_665edb6a-66f5-4b67-9ade-66df36e590fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_4a08d5fb-c9df-475a-9880-72de27c4c54f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_665edb6a-66f5-4b67-9ade-66df36e590fb" xlink:to="loc_us-gaap_CreditFacilityDomain_4a08d5fb-c9df-475a-9880-72de27c4c54f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_9ca96e3f-0cdc-4786-8940-0acf0f4574e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_4a08d5fb-c9df-475a-9880-72de27c4c54f" xlink:to="loc_us-gaap_LetterOfCreditMember_9ca96e3f-0cdc-4786-8940-0acf0f4574e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_0d7c834f-69e7-4b23-a05d-157248f18fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_95431783-1df0-4631-ae5f-db15146a003c" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_0d7c834f-69e7-4b23-a05d-157248f18fa3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/OtherCostsNetAdditionalInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#OtherCostsNetAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/OtherCostsNetAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b8253-f7f5-7289-a4cb-87f302ddce81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b8253-f7f5-7289-a4cb-87f302ddce81" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019b8253-f7f5-746c-820e-28ce72be17e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b8253-f7f5-7289-a4cb-87f302ddce81" xlink:to="loc_us-gaap_RestructuringPlanAxis_019b8253-f7f5-746c-820e-28ce72be17e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019b8253-f7f5-746c-820e-28ce72be17e8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019b8253-f7f5-746c-820e-28ce72be17e8" xlink:to="loc_us-gaap_RestructuringPlanDomain_019b8253-f7f5-746c-820e-28ce72be17e8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019b8253-f7f5-76eb-b383-f8c62b20faba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019b8253-f7f5-746c-820e-28ce72be17e8" xlink:to="loc_us-gaap_RestructuringPlanDomain_019b8253-f7f5-76eb-b383-f8c62b20faba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RestructuringPlan2025Member_019c6a9a-73e5-7e86-992b-141c3e1fc679" xlink:href="kai-20260103.xsd#kai_RestructuringPlan2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_019b8253-f7f5-76eb-b383-f8c62b20faba" xlink:to="loc_kai_RestructuringPlan2025Member_019c6a9a-73e5-7e86-992b-141c3e1fc679" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RestructuringPlan2023Member_019b8253-f7f5-79ba-8a4a-3c81da2c59b8" xlink:href="kai-20260103.xsd#kai_RestructuringPlan2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_019b8253-f7f5-76eb-b383-f8c62b20faba" xlink:to="loc_kai_RestructuringPlan2023Member_019b8253-f7f5-79ba-8a4a-3c81da2c59b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b8253-f7f5-7cee-844a-7cb08e09e114" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b8253-f7f5-7289-a4cb-87f302ddce81" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b8253-f7f5-7cee-844a-7cb08e09e114" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b8253-f7f5-7cee-844a-7cb08e09e114_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b8253-f7f5-7cee-844a-7cb08e09e114" xlink:to="loc_us-gaap_SegmentDomain_019b8253-f7f5-7cee-844a-7cb08e09e114_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b8253-f7f5-7c0c-80a9-045cdd26a6bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b8253-f7f5-7cee-844a-7cb08e09e114" xlink:to="loc_us-gaap_SegmentDomain_019b8253-f7f5-7c0c-80a9-045cdd26a6bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_IndustrialProcessingMember_019c2ce2-0010-7016-820f-ea3f76d2eb89" xlink:href="kai-20260103.xsd#kai_IndustrialProcessingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b8253-f7f5-7c0c-80a9-045cdd26a6bc" xlink:to="loc_kai_IndustrialProcessingMember_019c2ce2-0010-7016-820f-ea3f76d2eb89" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FlowControlMember_019b8253-f7f5-711d-94a4-bdc51d5dfd04" xlink:href="kai-20260103.xsd#kai_FlowControlMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b8253-f7f5-7c0c-80a9-045cdd26a6bc" xlink:to="loc_kai_FlowControlMember_019b8253-f7f5-711d-94a4-bdc51d5dfd04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019b8253-f7f5-76bb-8add-b3cc147346be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b8253-f7f5-7289-a4cb-87f302ddce81" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019b8253-f7f5-76bb-8add-b3cc147346be" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019b8253-f7f5-76bb-8add-b3cc147346be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019b8253-f7f5-76bb-8add-b3cc147346be" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019b8253-f7f5-76bb-8add-b3cc147346be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019b8253-f7f5-7ec8-8b01-ee1a2faf2446" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019b8253-f7f5-76bb-8add-b3cc147346be" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019b8253-f7f5-7ec8-8b01-ee1a2faf2446" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019b8253-f7f5-76ff-8ceb-745436c4a34d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019b8253-f7f5-7ec8-8b01-ee1a2faf2446" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019b8253-f7f5-76ff-8ceb-745436c4a34d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FacilityAndOtherClosureCostsMember_019b8253-f7f5-736a-a22e-467336a6f807" xlink:href="kai-20260103.xsd#kai_FacilityAndOtherClosureCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019b8253-f7f5-7ec8-8b01-ee1a2faf2446" xlink:to="loc_kai_FacilityAndOtherClosureCostsMember_019b8253-f7f5-736a-a22e-467336a6f807" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringSettlementAndImpairmentProvisions_019b8253-f7f5-7878-ad31-abf1d1f39901" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringSettlementAndImpairmentProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_RestructuringSettlementAndImpairmentProvisions_019b8253-f7f5-7878-ad31-abf1d1f39901" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019b8253-f7f5-7747-8f95-e765826410be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_RestructuringCharges_019b8253-f7f5-7747-8f95-e765826410be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019b8253-f7f5-723b-a2c0-5d43f33eba32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019b8253-f7f5-723b-a2c0-5d43f33eba32" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_019b8253-f7f5-7fcd-96fd-aac887c3ca8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_AssetImpairmentCharges_019b8253-f7f5-7fcd-96fd-aac887c3ca8e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ImpairmentLongLivedAssetHeldForUseNonCash_019c7c1a-c129-71b3-802c-43ed0c31432e" xlink:href="kai-20260103.xsd#kai_ImpairmentLongLivedAssetHeldForUseNonCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetImpairmentCharges_019b8253-f7f5-7fcd-96fd-aac887c3ca8e" xlink:to="loc_kai_ImpairmentLongLivedAssetHeldForUseNonCash_019c7c1a-c129-71b3-802c-43ed0c31432e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringCosts_019c03bc-b389-7b64-949e-9fafd48e7149" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherRestructuringCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_OtherRestructuringCosts_019c03bc-b389-7b64-949e-9fafd48e7149" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncome_019b8254-27ed-730b-9615-663094fa11fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_OtherIncome_019b8254-27ed-730b-9615-663094fa11fe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessExitCosts1_019b8254-27ed-7cd7-b0b8-89b231cc5eed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessExitCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b8253-f7f5-79f6-899d-90e767ce3512" xlink:to="loc_us-gaap_BusinessExitCosts1_019b8254-27ed-7cd7-b0b8-89b231cc5eed" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/OtherCostsNetChangesinAccruedRestructuringDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#OtherCostsNetChangesinAccruedRestructuringDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/OtherCostsNetChangesinAccruedRestructuringDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_746cb8ba-0c16-46af-9c3b-9bae48900ca8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_5999ce5a-4412-4d95-93eb-9f13c3a91b99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_746cb8ba-0c16-46af-9c3b-9bae48900ca8" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_5999ce5a-4412-4d95-93eb-9f13c3a91b99" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_e0c9e4c7-bd0d-4f44-a8a2-d4fd1000b427" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_5999ce5a-4412-4d95-93eb-9f13c3a91b99" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_e0c9e4c7-bd0d-4f44-a8a2-d4fd1000b427" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_e0c9e4c7-bd0d-4f44-a8a2-d4fd1000b427_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_e0c9e4c7-bd0d-4f44-a8a2-d4fd1000b427" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_e0c9e4c7-bd0d-4f44-a8a2-d4fd1000b427_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_2e61a3e7-cf01-4a69-97b0-42e75fcfeb15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_e0c9e4c7-bd0d-4f44-a8a2-d4fd1000b427" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_2e61a3e7-cf01-4a69-97b0-42e75fcfeb15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_75bfe6fe-9778-42f7-ade2-87471c7e94b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_2e61a3e7-cf01-4a69-97b0-42e75fcfeb15" xlink:to="loc_us-gaap_EmployeeSeveranceMember_75bfe6fe-9778-42f7-ade2-87471c7e94b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractTerminationMember_984b34b2-3afa-4f6c-8bc4-c4a2cd0ecfce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractTerminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_2e61a3e7-cf01-4a69-97b0-42e75fcfeb15" xlink:to="loc_us-gaap_ContractTerminationMember_984b34b2-3afa-4f6c-8bc4-c4a2cd0ecfce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FacilityAndOtherClosureCostsMember_3a0ca412-8012-4e09-a50e-3cade6d5530d" xlink:href="kai-20260103.xsd#kai_FacilityAndOtherClosureCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_2e61a3e7-cf01-4a69-97b0-42e75fcfeb15" xlink:to="loc_kai_FacilityAndOtherClosureCostsMember_3a0ca412-8012-4e09-a50e-3cade6d5530d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_45361655-45f0-4b17-8ca5-194ec125b786" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_5999ce5a-4412-4d95-93eb-9f13c3a91b99" xlink:to="loc_us-gaap_RestructuringPlanAxis_45361655-45f0-4b17-8ca5-194ec125b786" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_45361655-45f0-4b17-8ca5-194ec125b786_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_45361655-45f0-4b17-8ca5-194ec125b786" xlink:to="loc_us-gaap_RestructuringPlanDomain_45361655-45f0-4b17-8ca5-194ec125b786_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_685dce32-d026-4b0e-b25c-b98f3fad0a11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_45361655-45f0-4b17-8ca5-194ec125b786" xlink:to="loc_us-gaap_RestructuringPlanDomain_685dce32-d026-4b0e-b25c-b98f3fad0a11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RestructuringPlan2023Member_dbca761f-00b8-4aba-93ac-c96317aee0f6" xlink:href="kai-20260103.xsd#kai_RestructuringPlan2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_685dce32-d026-4b0e-b25c-b98f3fad0a11" xlink:to="loc_kai_RestructuringPlan2023Member_dbca761f-00b8-4aba-93ac-c96317aee0f6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_98e63142-22a1-4a75-8813-4dabda87e4b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_746cb8ba-0c16-46af-9c3b-9bae48900ca8" xlink:to="loc_us-gaap_RestructuringReserveRollForward_98e63142-22a1-4a75-8813-4dabda87e4b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_793d11fd-ec85-47f3-80e5-fd6bca8835d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_98e63142-22a1-4a75-8813-4dabda87e4b9" xlink:to="loc_us-gaap_RestructuringReserve_793d11fd-ec85-47f3-80e5-fd6bca8835d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_d338ecfc-e1c0-47b8-aea4-3e7c86fd9f19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_98e63142-22a1-4a75-8813-4dabda87e4b9" xlink:to="loc_us-gaap_RestructuringCharges_d338ecfc-e1c0-47b8-aea4-3e7c86fd9f19" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_58b47afc-af49-496f-95f9-59b868e3fc79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_98e63142-22a1-4a75-8813-4dabda87e4b9" xlink:to="loc_us-gaap_PaymentsForRestructuring_58b47afc-af49-496f-95f9-59b868e3fc79" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveTranslationAdjustment_08fa0adf-8608-4894-990f-f979260ca3fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveTranslationAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_98e63142-22a1-4a75-8813-4dabda87e4b9" xlink:to="loc_us-gaap_RestructuringReserveTranslationAdjustment_08fa0adf-8608-4894-990f-f979260ca3fc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_3d8dc9fd-1162-46df-a634-9c87c1a01218" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/LeasesAdditionalInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#LeasesAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/LeasesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_9db406a3-84c8-4c54-a9ba-947b604ed5db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_6bf87d38-649c-478f-a1e9-097a232b96fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9db406a3-84c8-4c54-a9ba-947b604ed5db" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_6bf87d38-649c-478f-a1e9-097a232b96fe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_f357971d-51f4-4247-942f-548b43b4fa91" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_6bf87d38-649c-478f-a1e9-097a232b96fe" xlink:to="loc_srt_StatementGeographicalAxis_f357971d-51f4-4247-942f-548b43b4fa91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_f357971d-51f4-4247-942f-548b43b4fa91_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_f357971d-51f4-4247-942f-548b43b4fa91" xlink:to="loc_srt_SegmentGeographicalDomain_f357971d-51f4-4247-942f-548b43b4fa91_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_973d9b3d-d06f-4ad9-bd2f-430b3150dc09" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_f357971d-51f4-4247-942f-548b43b4fa91" xlink:to="loc_srt_SegmentGeographicalDomain_973d9b3d-d06f-4ad9-bd2f-430b3150dc09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_16b395c2-d0ee-4426-a1d9-83b4ff3e8c6f" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_973d9b3d-d06f-4ad9-bd2f-430b3150dc09" xlink:to="loc_country_CA_16b395c2-d0ee-4426-a1d9-83b4ff3e8c6f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_LeaseOptiontoExtendTerm_0f9c7daa-1505-45a4-b64a-a0d5926d1b09" xlink:href="kai-20260103.xsd#kai_LeaseOptiontoExtendTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_9db406a3-84c8-4c54-a9ba-947b604ed5db" xlink:to="loc_kai_LeaseOptiontoExtendTerm_0f9c7daa-1505-45a4-b64a-a0d5926d1b09" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/LeasesSupplementalCashFlowInformationRelatedtoLeasesDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#LeasesSupplementalCashFlowInformationRelatedtoLeasesDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/LeasesSupplementalCashFlowInformationRelatedtoLeasesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_3bb15c92-5d01-4aef-bc94-565807cbc476" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_75e3f67c-f30c-4154-8040-942464d7c786" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3bb15c92-5d01-4aef-bc94-565807cbc476" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_75e3f67c-f30c-4154-8040-942464d7c786" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_920ea5cc-2094-4faf-ad13-c76ff6c5c8c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_75e3f67c-f30c-4154-8040-942464d7c786" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_920ea5cc-2094-4faf-ad13-c76ff6c5c8c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_920ea5cc-2094-4faf-ad13-c76ff6c5c8c4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_920ea5cc-2094-4faf-ad13-c76ff6c5c8c4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_920ea5cc-2094-4faf-ad13-c76ff6c5c8c4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b00c0bb5-0e6f-4e47-930d-78716b07d5c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_920ea5cc-2094-4faf-ad13-c76ff6c5c8c4" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b00c0bb5-0e6f-4e47-930d-78716b07d5c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2025AcquisitionMember_019caeb1-8d81-792a-a2b4-838ffd7cd3b6" xlink:href="kai-20260103.xsd#kai_A2025AcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b00c0bb5-0e6f-4e47-930d-78716b07d5c6" xlink:to="loc_kai_A2025AcquisitionMember_019caeb1-8d81-792a-a2b4-838ffd7cd3b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_A2024AcquisitionsMember_66de756c-bcc7-43ba-b00b-91f2176643bd" xlink:href="kai-20260103.xsd#kai_A2024AcquisitionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b00c0bb5-0e6f-4e47-930d-78716b07d5c6" xlink:to="loc_kai_A2024AcquisitionsMember_66de756c-bcc7-43ba-b00b-91f2176643bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_CashPaidForAmountsIncludedInTheMeasurementOfLeaseLiabilitiesAbstract_292d1962-0ca1-4890-9056-231b9de18e51" xlink:href="kai-20260103.xsd#kai_CashPaidForAmountsIncludedInTheMeasurementOfLeaseLiabilitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3bb15c92-5d01-4aef-bc94-565807cbc476" xlink:to="loc_kai_CashPaidForAmountsIncludedInTheMeasurementOfLeaseLiabilitiesAbstract_292d1962-0ca1-4890-9056-231b9de18e51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_8aa98b08-29f7-4718-854c-85ecf4c6eec1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_CashPaidForAmountsIncludedInTheMeasurementOfLeaseLiabilitiesAbstract_292d1962-0ca1-4890-9056-231b9de18e51" xlink:to="loc_us-gaap_OperatingLeasePayments_8aa98b08-29f7-4718-854c-85ecf4c6eec1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_439c42a9-5684-44ca-be19-3ab300c59016" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseInterestPaymentOnLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_CashPaidForAmountsIncludedInTheMeasurementOfLeaseLiabilitiesAbstract_292d1962-0ca1-4890-9056-231b9de18e51" xlink:to="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_439c42a9-5684-44ca-be19-3ab300c59016" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_c7eb05d2-ea95-4b77-84c4-1628b2cb3e9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_CashPaidForAmountsIncludedInTheMeasurementOfLeaseLiabilitiesAbstract_292d1962-0ca1-4890-9056-231b9de18e51" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_c7eb05d2-ea95-4b77-84c4-1628b2cb3e9e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract_3fe67ccc-6544-40c0-a425-39f4659ffa45" xlink:href="kai-20260103.xsd#kai_RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3bb15c92-5d01-4aef-bc94-565807cbc476" xlink:to="loc_kai_RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract_3fe67ccc-6544-40c0-a425-39f4659ffa45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_f8bcf1e5-9d20-4a86-acd7-08e5c380b206" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract_3fe67ccc-6544-40c0-a425-39f4659ffa45" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_f8bcf1e5-9d20-4a86-acd7-08e5c380b206" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_0ed8284f-6856-41bd-a45f-f85e65fe3fbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_kai_RightOfUseAssetsObtainedInExchangeForLeaseObligationsAbstract_3fe67ccc-6544-40c0-a425-39f4659ffa45" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_0ed8284f-6856-41bd-a45f-f85e65fe3fbe" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsAssetsandLiabilitiesRecurringBasisDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#FairValueMeasurementsandFairValueofFinancialInstrumentsAssetsandLiabilitiesRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsAssetsandLiabilitiesRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_14769ade-d4db-45f7-934a-6d93a495b220" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c55f55f7-d451-45de-ab37-d1c8e8127ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_14769ade-d4db-45f7-934a-6d93a495b220" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c55f55f7-d451-45de-ab37-d1c8e8127ecd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9717f86f-2d1a-43e1-bbad-0cd295f697f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_c55f55f7-d451-45de-ab37-d1c8e8127ecd" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9717f86f-2d1a-43e1-bbad-0cd295f697f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9717f86f-2d1a-43e1-bbad-0cd295f697f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9717f86f-2d1a-43e1-bbad-0cd295f697f9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_9717f86f-2d1a-43e1-bbad-0cd295f697f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7850ccf8-16fe-46bd-93cd-5935521fc3bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_9717f86f-2d1a-43e1-bbad-0cd295f697f9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7850ccf8-16fe-46bd-93cd-5935521fc3bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_d26a3347-47cd-431e-afad-46b07756076f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7850ccf8-16fe-46bd-93cd-5935521fc3bd" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_d26a3347-47cd-431e-afad-46b07756076f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_effc0750-3ae1-45d4-a710-5773bd732dd0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7850ccf8-16fe-46bd-93cd-5935521fc3bd" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_effc0750-3ae1-45d4-a710-5773bd732dd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_c1770398-850c-49e9-957b-6bbd2440f62c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7850ccf8-16fe-46bd-93cd-5935521fc3bd" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_c1770398-850c-49e9-957b-6bbd2440f62c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_3dceb045-8489-48e2-9e4f-3c01aa25cb0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_14769ade-d4db-45f7-934a-6d93a495b220" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_3dceb045-8489-48e2-9e4f-3c01aa25cb0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_1fedab00-bb5d-465d-b29b-7d440b563b94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_3dceb045-8489-48e2-9e4f-3c01aa25cb0c" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_1fedab00-bb5d-465d-b29b-7d440b563b94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BankersAcceptanceDraftsFairValueDisclosure_556a130a-a525-4303-b0d7-52bb0e907ff7" xlink:href="kai-20260103.xsd#kai_BankersAcceptanceDraftsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_3dceb045-8489-48e2-9e4f-3c01aa25cb0c" xlink:to="loc_kai_BankersAcceptanceDraftsFairValueDisclosure_556a130a-a525-4303-b0d7-52bb0e907ff7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1d5e7a9b-a44b-4641-a020-9ab4bcfe6ab1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_14769ade-d4db-45f7-934a-6d93a495b220" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1d5e7a9b-a44b-4641-a020-9ab4bcfe6ab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_f9f23174-eb0f-4fbc-90ab-1b2feb709458" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1d5e7a9b-a44b-4641-a020-9ab4bcfe6ab1" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_f9f23174-eb0f-4fbc-90ab-1b2feb709458" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_307dc184-772e-4b41-beb3-ce69ecab311d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1d5e7a9b-a44b-4641-a020-9ab4bcfe6ab1" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_307dc184-772e-4b41-beb3-ce69ecab311d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsFairValueofContingentConsiderationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#FairValueMeasurementsandFairValueofFinancialInstrumentsFairValueofContingentConsiderationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsFairValueofContingentConsiderationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_748047d5-5ba2-4a7f-ac69-7c58ad49bece" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_fab08d30-76eb-4d88-b6c3-1ad09690c1d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_748047d5-5ba2-4a7f-ac69-7c58ad49bece" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_fab08d30-76eb-4d88-b6c3-1ad09690c1d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_975b2fed-812e-4673-b56c-e596ea5bc254" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_fab08d30-76eb-4d88-b6c3-1ad09690c1d2" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_975b2fed-812e-4673-b56c-e596ea5bc254" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_975b2fed-812e-4673-b56c-e596ea5bc254_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_975b2fed-812e-4673-b56c-e596ea5bc254" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_975b2fed-812e-4673-b56c-e596ea5bc254_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0063b242-9963-4db4-ba84-b313ac6433d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_975b2fed-812e-4673-b56c-e596ea5bc254" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0063b242-9963-4db4-ba84-b313ac6433d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_ContingentConsiderationLiabilityMember_f8efb13d-4d1a-4774-9cab-12e2177cec49" xlink:href="kai-20260103.xsd#kai_ContingentConsiderationLiabilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_0063b242-9963-4db4-ba84-b313ac6433d4" xlink:to="loc_kai_ContingentConsiderationLiabilityMember_f8efb13d-4d1a-4774-9cab-12e2177cec49" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_23b7acfe-e802-46f7-9517-e977cb3a013b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_748047d5-5ba2-4a7f-ac69-7c58ad49bece" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_23b7acfe-e802-46f7-9517-e977cb3a013b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_e26c5715-2be2-478b-a243-7f95a209390b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_23b7acfe-e802-46f7-9517-e977cb3a013b" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_e26c5715-2be2-478b-a243-7f95a209390b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityInterestAccretion_019bb2d0-bd56-79ee-893f-0e2ee585178e" xlink:href="kai-20260103.xsd#kai_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityInterestAccretion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_23b7acfe-e802-46f7-9517-e977cb3a013b" xlink:to="loc_kai_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityInterestAccretion_019bb2d0-bd56-79ee-893f-0e2ee585178e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityForeignCurrencyTranslation_92733512-fc1b-46bd-a9a2-9c974143611b" xlink:href="kai-20260103.xsd#kai_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityForeignCurrencyTranslation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_23b7acfe-e802-46f7-9517-e977cb3a013b" xlink:to="loc_kai_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityForeignCurrencyTranslation_92733512-fc1b-46bd-a9a2-9c974143611b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_4ea512b1-36df-42ca-accf-a5197ca803d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsDebtObligationsDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#FairValueMeasurementsandFairValueofFinancialInstrumentsDebtObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsDebtObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_d378b278-60d0-4bd1-ac85-6844d513c401" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_0507f5cc-471a-4178-8641-500df479aa60" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_d378b278-60d0-4bd1-ac85-6844d513c401" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_0507f5cc-471a-4178-8641-500df479aa60" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_417dd8d7-3954-412a-8555-64d4d91a009b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_0507f5cc-471a-4178-8641-500df479aa60" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_417dd8d7-3954-412a-8555-64d4d91a009b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_417dd8d7-3954-412a-8555-64d4d91a009b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_417dd8d7-3954-412a-8555-64d4d91a009b" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_417dd8d7-3954-412a-8555-64d4d91a009b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_2016954a-7395-472e-a701-2f687a566db3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_417dd8d7-3954-412a-8555-64d4d91a009b" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_2016954a-7395-472e-a701-2f687a566db3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b8db0-7346-7fea-bf2f-4951bbb90bd0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_2016954a-7395-472e-a701-2f687a566db3" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b8db0-7346-7fea-bf2f-4951bbb90bd0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_84d2f2a2-42db-45cb-8eff-3f862ccdc917" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b8db0-7346-7fea-bf2f-4951bbb90bd0" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_84d2f2a2-42db-45cb-8eff-3f862ccdc917" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_ada08883-afe3-450c-bb0b-f5eac765816d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b8db0-7346-7fea-bf2f-4951bbb90bd0" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_ada08883-afe3-450c-bb0b-f5eac765816d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_0039a6e1-3262-4eb6-ac05-3ef1ba36e1ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_0507f5cc-471a-4178-8641-500df479aa60" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_0039a6e1-3262-4eb6-ac05-3ef1ba36e1ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_0039a6e1-3262-4eb6-ac05-3ef1ba36e1ef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_0039a6e1-3262-4eb6-ac05-3ef1ba36e1ef" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_0039a6e1-3262-4eb6-ac05-3ef1ba36e1ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_9aaa5d7f-667c-46fd-84c5-87f0d099c429" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_0039a6e1-3262-4eb6-ac05-3ef1ba36e1ef" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_9aaa5d7f-667c-46fd-84c5-87f0d099c429" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_30970f8b-6dd4-4fd4-a6a6-270b6469fa28" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9aaa5d7f-667c-46fd-84c5-87f0d099c429" xlink:to="loc_us-gaap_LineOfCreditMember_30970f8b-6dd4-4fd4-a6a6-270b6469fa28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_8ad06938-7fff-42ae-aea1-3bf13598179d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9aaa5d7f-667c-46fd-84c5-87f0d099c429" xlink:to="loc_us-gaap_SeniorNotesMember_8ad06938-7fff-42ae-aea1-3bf13598179d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_OtherBorrowingsMember_1885b197-13b7-43b1-a08c-635e76f2c4a3" xlink:href="kai-20260103.xsd#kai_OtherBorrowingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_9aaa5d7f-667c-46fd-84c5-87f0d099c429" xlink:to="loc_kai_OtherBorrowingsMember_1885b197-13b7-43b1-a08c-635e76f2c4a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_8a8628e3-4306-4b25-bc01-ca2c3554e1cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_d378b278-60d0-4bd1-ac85-6844d513c401" xlink:to="loc_us-gaap_DebtInstrumentFairValue_8a8628e3-4306-4b25-bc01-ca2c3554e1cf" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/BusinessSegmentandGeographicalInformationSummaryofReportableSegmentsDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#BusinessSegmentandGeographicalInformationSummaryofReportableSegmentsDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/BusinessSegmentandGeographicalInformationSummaryofReportableSegmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7f55d4e-9b07-4e68-845e-395399c15eda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7f55d4e-9b07-4e68-845e-395399c15eda" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_fd7cc5df-8225-4457-a872-a04709a54652" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7f55d4e-9b07-4e68-845e-395399c15eda" xlink:to="loc_srt_ConsolidationItemsAxis_fd7cc5df-8225-4457-a872-a04709a54652" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_fd7cc5df-8225-4457-a872-a04709a54652_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_fd7cc5df-8225-4457-a872-a04709a54652" xlink:to="loc_srt_ConsolidationItemsDomain_fd7cc5df-8225-4457-a872-a04709a54652_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_092b3808-529a-4a03-94d2-e7e708032d3e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_fd7cc5df-8225-4457-a872-a04709a54652" xlink:to="loc_srt_ConsolidationItemsDomain_092b3808-529a-4a03-94d2-e7e708032d3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_c5e9f530-42c7-4480-a970-f8bec2606808" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_092b3808-529a-4a03-94d2-e7e708032d3e" xlink:to="loc_us-gaap_OperatingSegmentsMember_c5e9f530-42c7-4480-a970-f8bec2606808" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_d5b0077c-4331-4eba-a500-75a81a3ef4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_092b3808-529a-4a03-94d2-e7e708032d3e" xlink:to="loc_us-gaap_CorporateNonSegmentMember_d5b0077c-4331-4eba-a500-75a81a3ef4e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_0e897446-c3ff-458c-b384-2d7c6763522e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7f55d4e-9b07-4e68-845e-395399c15eda" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_0e897446-c3ff-458c-b384-2d7c6763522e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0e897446-c3ff-458c-b384-2d7c6763522e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0e897446-c3ff-458c-b384-2d7c6763522e" xlink:to="loc_us-gaap_SegmentDomain_0e897446-c3ff-458c-b384-2d7c6763522e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_03579b15-e3b4-4418-848f-9f2a8d994072" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0e897446-c3ff-458c-b384-2d7c6763522e" xlink:to="loc_us-gaap_SegmentDomain_03579b15-e3b4-4418-848f-9f2a8d994072" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_FlowControlMember_4969a818-2a5d-4a42-9053-be5ce1930706" xlink:href="kai-20260103.xsd#kai_FlowControlMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_03579b15-e3b4-4418-848f-9f2a8d994072" xlink:to="loc_kai_FlowControlMember_4969a818-2a5d-4a42-9053-be5ce1930706" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_IndustrialProcessingMember_d3e1a09c-ddaf-4f6a-9782-05546ab14af2" xlink:href="kai-20260103.xsd#kai_IndustrialProcessingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_03579b15-e3b4-4418-848f-9f2a8d994072" xlink:to="loc_kai_IndustrialProcessingMember_d3e1a09c-ddaf-4f6a-9782-05546ab14af2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_MaterialHandlingSystemsMember_d9470a3f-13cc-408f-accd-2dc19224d49f" xlink:href="kai-20260103.xsd#kai_MaterialHandlingSystemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_03579b15-e3b4-4418-848f-9f2a8d994072" xlink:to="loc_kai_MaterialHandlingSystemsMember_d9470a3f-13cc-408f-accd-2dc19224d49f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_8bb003b9-8832-4a4c-ac4e-83e704cd1737" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7f55d4e-9b07-4e68-845e-395399c15eda" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_8bb003b9-8832-4a4c-ac4e-83e704cd1737" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8bb003b9-8832-4a4c-ac4e-83e704cd1737_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_8bb003b9-8832-4a4c-ac4e-83e704cd1737" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8bb003b9-8832-4a4c-ac4e-83e704cd1737_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50bcfc59-6bbe-47fc-bc7a-94f2bd75854e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_8bb003b9-8832-4a4c-ac4e-83e704cd1737" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50bcfc59-6bbe-47fc-bc7a-94f2bd75854e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndBuildingMember_f39f22b2-010c-4059-8bf2-efb52a873129" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandAndBuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50bcfc59-6bbe-47fc-bc7a-94f2bd75854e" xlink:to="loc_us-gaap_LandAndBuildingMember_f39f22b2-010c-4059-8bf2-efb52a873129" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_362c2ec6-caab-4c3b-a665-d2d0af3b7c09" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_c7f55d4e-9b07-4e68-845e-395399c15eda" xlink:to="loc_srt_StatementGeographicalAxis_362c2ec6-caab-4c3b-a665-d2d0af3b7c09" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_362c2ec6-caab-4c3b-a665-d2d0af3b7c09_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_362c2ec6-caab-4c3b-a665-d2d0af3b7c09" xlink:to="loc_srt_SegmentGeographicalDomain_362c2ec6-caab-4c3b-a665-d2d0af3b7c09_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_3b1d3e08-457d-4622-98b7-3a82398101f0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_362c2ec6-caab-4c3b-a665-d2d0af3b7c09" xlink:to="loc_srt_SegmentGeographicalDomain_3b1d3e08-457d-4622-98b7-3a82398101f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_eac4bbae-1471-4e57-bfb4-1cb843c78eb7" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_3b1d3e08-457d-4622-98b7-3a82398101f0" xlink:to="loc_country_CN_eac4bbae-1471-4e57-bfb4-1cb843c78eb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_65bed95b-95ab-49f0-86be-3894c0c27d9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_65bed95b-95ab-49f0-86be-3894c0c27d9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_42be12be-0701-4d87-ae92-4505bdc576e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_42be12be-0701-4d87-ae92-4505bdc576e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_32bff5ca-eaf6-4873-b0cc-17048c6ee6a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_GrossProfit_32bff5ca-eaf6-4873-b0cc-17048c6ee6a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_GrossProfitMarginPercent_87105b00-97e0-400f-8387-b1dbc543e486" xlink:href="kai-20260103.xsd#kai_GrossProfitMarginPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_kai_GrossProfitMarginPercent_87105b00-97e0-400f-8387-b1dbc543e486" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_99c1eeb0-9d7c-41fb-864b-10459eacc0a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_OperatingExpensesAbstract_99c1eeb0-9d7c-41fb-864b-10459eacc0a4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingExpense_e064c77d-05f2-4753-b743-ea5c26213942" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_99c1eeb0-9d7c-41fb-864b-10459eacc0a4" xlink:to="loc_us-gaap_SellingExpense_e064c77d-05f2-4753-b743-ea5c26213942" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_1938e278-2233-495d-bdf5-747836d751c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_99c1eeb0-9d7c-41fb-864b-10459eacc0a4" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_1938e278-2233-495d-bdf5-747836d751c3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_2cb5aaae-612a-4820-99a8-c79905103372" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_99c1eeb0-9d7c-41fb-864b-10459eacc0a4" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_2cb5aaae-612a-4820-99a8-c79905103372" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_51486009-143e-49f4-a8ab-5c41377237d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_99c1eeb0-9d7c-41fb-864b-10459eacc0a4" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_51486009-143e-49f4-a8ab-5c41377237d3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_dc1eb86d-6968-4ae5-952c-082d89c95b59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_99c1eeb0-9d7c-41fb-864b-10459eacc0a4" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_dc1eb86d-6968-4ae5-952c-082d89c95b59" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_f7c6b81e-8d07-4462-8da9-690dd15d0d71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_OperatingIncomeLoss_f7c6b81e-8d07-4462-8da9-690dd15d0d71" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_SegmentOperatingIncomeMarginPercent_34055cf1-3e59-48ce-8283-33e41a46d581" xlink:href="kai-20260103.xsd#kai_SegmentOperatingIncomeMarginPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_kai_SegmentOperatingIncomeMarginPercent_34055cf1-3e59-48ce-8283-33e41a46d581" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_1f9a7efd-f853-4539-ba18-726f9956b2a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_InterestExpenseNonoperatingNet_e8c54537-ccc9-4d28-b3b7-b6e1ea23f263" xlink:href="kai-20260103.xsd#kai_InterestExpenseNonoperatingNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_kai_InterestExpenseNonoperatingNet_e8c54537-ccc9-4d28-b3b7-b6e1ea23f263" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_683e70bd-bf27-4d2a-8742-39ed081692f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_OtherNonoperatingExpense_683e70bd-bf27-4d2a-8742-39ed081692f0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e0dc50f3-4d22-4f67-9440-91ef5cfa1156" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e0dc50f3-4d22-4f67-9440-91ef5cfa1156" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_af270b1e-531d-4af5-94ed-9ca12410d133" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_Depreciation_af270b1e-531d-4af5-94ed-9ca12410d133" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_d4769657-8a09-4ead-aaae-046e8894f018" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_Assets_d4769657-8a09-4ead-aaae-046e8894f018" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_8562f463-6d7f-46b6-9b4c-ef25bf014045" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9661426f-fe30-49d5-945c-45e4d0fdf2f4" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_8562f463-6d7f-46b6-9b4c-ef25bf014045" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/BusinessSegmentandGeographicalInformationSummaryofRevenueandLongLivedAssetsbyGeographicalAreaDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#BusinessSegmentandGeographicalInformationSummaryofRevenueandLongLivedAssetsbyGeographicalAreaDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/BusinessSegmentandGeographicalInformationSummaryofRevenueandLongLivedAssetsbyGeographicalAreaDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_6be4a97d-15f8-47c7-897c-1f896535277f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_b8e2e19a-1837-4dce-a857-00515540f741" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_6be4a97d-15f8-47c7-897c-1f896535277f" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_b8e2e19a-1837-4dce-a857-00515540f741" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_ff6223f4-e93d-4141-abaa-58e0b2e0cbfa" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_b8e2e19a-1837-4dce-a857-00515540f741" xlink:to="loc_srt_StatementGeographicalAxis_ff6223f4-e93d-4141-abaa-58e0b2e0cbfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_ff6223f4-e93d-4141-abaa-58e0b2e0cbfa_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_ff6223f4-e93d-4141-abaa-58e0b2e0cbfa" xlink:to="loc_srt_SegmentGeographicalDomain_ff6223f4-e93d-4141-abaa-58e0b2e0cbfa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_ff6223f4-e93d-4141-abaa-58e0b2e0cbfa" xlink:to="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_e48d369e-8b47-422b-9bbd-66325a996afd" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:to="loc_country_US_e48d369e-8b47-422b-9bbd-66325a996afd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_d72869a3-5276-4898-866a-63d90cee8e7f" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:to="loc_country_CA_d72869a3-5276-4898-866a-63d90cee8e7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_65fefc55-8da2-41e6-994c-c7e1e707c1f2" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:to="loc_country_CN_65fefc55-8da2-41e6-994c-c7e1e707c1f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_DE_ceb9f77a-1b71-41df-bcdf-8d2611320635" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_DE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:to="loc_country_DE_ceb9f77a-1b71-41df-bcdf-8d2611320635" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_FI_b63e033e-4cb9-425b-87e8-d7c3118e8a32" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_FI"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:to="loc_country_FI_b63e033e-4cb9-425b-87e8-d7c3118e8a32" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_SegmentGeographicalGroupsOfCountriesOtherCountriesMember_0eb4807b-19ab-4328-aa74-202c1f431869" xlink:href="kai-20260103.xsd#kai_SegmentGeographicalGroupsOfCountriesOtherCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_f592fc58-3764-4479-8d8a-2778036cf5ea" xlink:to="loc_kai_SegmentGeographicalGroupsOfCountriesOtherCountriesMember_0eb4807b-19ab-4328-aa74-202c1f431869" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_8c207fea-6e26-411c-aeae-851ec4692cb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_6be4a97d-15f8-47c7-897c-1f896535277f" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_8c207fea-6e26-411c-aeae-851ec4692cb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_b5a46919-6d0c-4f86-bb57-61bb802b3e36" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_6be4a97d-15f8-47c7-897c-1f896535277f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_b5a46919-6d0c-4f86-bb57-61bb802b3e36" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/EarningsperShareAdditionalInformationDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#EarningsperShareAdditionalInformationDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/EarningsperShareAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d0784cb7-1f0e-44be-ac49-33c2942fe808" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_64754f50-a3ed-448e-84f6-b5ce8bb03625" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d0784cb7-1f0e-44be-ac49-33c2942fe808" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_64754f50-a3ed-448e-84f6-b5ce8bb03625" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1e4e5745-5929-4530-989f-426515b3258d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_64754f50-a3ed-448e-84f6-b5ce8bb03625" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1e4e5745-5929-4530-989f-426515b3258d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1e4e5745-5929-4530-989f-426515b3258d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1e4e5745-5929-4530-989f-426515b3258d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_1e4e5745-5929-4530-989f-426515b3258d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_fc04fb01-8088-4a3c-95a2-86f045d90b63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1e4e5745-5929-4530-989f-426515b3258d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_fc04fb01-8088-4a3c-95a2-86f045d90b63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_21e3e5ca-b05f-4702-b264-bdd7fadb3f24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_fc04fb01-8088-4a3c-95a2-86f045d90b63" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_21e3e5ca-b05f-4702-b264-bdd7fadb3f24" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_e190045d-5ee8-4fc5-b0a7-8a9f31ec3c98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_d0784cb7-1f0e-44be-ac49-33c2942fe808" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_e190045d-5ee8-4fc5-b0a7-8a9f31ec3c98" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/AccumulatedOtherComprehensiveItemsComponentsofAOCIontheBalanceSheetDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#AccumulatedOtherComprehensiveItemsComponentsofAOCIontheBalanceSheetDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/AccumulatedOtherComprehensiveItemsComponentsofAOCIontheBalanceSheetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_588a75c5-146e-4fd1-8665-832f7a1b8451" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_52d96ff7-0df5-42e1-b332-2f414604d03d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_588a75c5-146e-4fd1-8665-832f7a1b8451" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_52d96ff7-0df5-42e1-b332-2f414604d03d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_21bab1aa-3fd4-4392-9cdd-963aa058249a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_52d96ff7-0df5-42e1-b332-2f414604d03d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_21bab1aa-3fd4-4392-9cdd-963aa058249a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_21bab1aa-3fd4-4392-9cdd-963aa058249a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_21bab1aa-3fd4-4392-9cdd-963aa058249a" xlink:to="loc_us-gaap_EquityComponentDomain_21bab1aa-3fd4-4392-9cdd-963aa058249a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_32e8fe4f-4023-4840-869e-305fcc24ec70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_21bab1aa-3fd4-4392-9cdd-963aa058249a" xlink:to="loc_us-gaap_EquityComponentDomain_32e8fe4f-4023-4840-869e-305fcc24ec70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_d483f6eb-224a-42c4-b94d-3627346fd9a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_32e8fe4f-4023-4840-869e-305fcc24ec70" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_d483f6eb-224a-42c4-b94d-3627346fd9a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_cf0b915d-a8ad-4712-a5d2-be19daccc192" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_d483f6eb-224a-42c4-b94d-3627346fd9a3" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_cf0b915d-a8ad-4712-a5d2-be19daccc192" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_20a53ab5-7bc4-415e-b341-f7a3f9adacec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_d483f6eb-224a-42c4-b94d-3627346fd9a3" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_20a53ab5-7bc4-415e-b341-f7a3f9adacec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_05e26f73-29a4-4aca-bcbc-15cc5ecfbd5f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_588a75c5-146e-4fd1-8665-832f7a1b8451" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_05e26f73-29a4-4aca-bcbc-15cc5ecfbd5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_5e321ffd-e6f5-45ed-b0cf-93086c61a631" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_05e26f73-29a4-4aca-bcbc-15cc5ecfbd5f" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_5e321ffd-e6f5-45ed-b0cf-93086c61a631" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_e8ba4eb6-1421-4b65-bed6-2b386d89dacc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_05e26f73-29a4-4aca-bcbc-15cc5ecfbd5f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_e8ba4eb6-1421-4b65-bed6-2b386d89dacc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_19a3c2e7-7119-4d76-93e6-4caec7a74751" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_05e26f73-29a4-4aca-bcbc-15cc5ecfbd5f" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_19a3c2e7-7119-4d76-93e6-4caec7a74751" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_d42e4d00-a97f-4b3e-9135-aea14b32356b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTaxAbstract_05e26f73-29a4-4aca-bcbc-15cc5ecfbd5f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_d42e4d00-a97f-4b3e-9135-aea14b32356b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_2abd6bee-39ab-4b58-97d0-5d183a398a95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/AccumulatedOtherComprehensiveItemsReclassificationOutofAOCIDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#AccumulatedOtherComprehensiveItemsReclassificationOutofAOCIDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/AccumulatedOtherComprehensiveItemsReclassificationOutofAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_c3243c55-987f-4a79-bd4c-b4ba0fa7794f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_c3243c55-987f-4a79-bd4c-b4ba0fa7794f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_0d2e8f79-47bd-4c08-b7b7-2cb92ae59e32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_c3243c55-987f-4a79-bd4c-b4ba0fa7794f" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_0d2e8f79-47bd-4c08-b7b7-2cb92ae59e32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_0d2e8f79-47bd-4c08-b7b7-2cb92ae59e32_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_0d2e8f79-47bd-4c08-b7b7-2cb92ae59e32" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_0d2e8f79-47bd-4c08-b7b7-2cb92ae59e32_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_67304f27-6ca0-4d47-ba9c-0231219a8358" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_0d2e8f79-47bd-4c08-b7b7-2cb92ae59e32" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_67304f27-6ca0-4d47-ba9c-0231219a8358" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_d98c6335-39f4-4815-af22-520c75c07e78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_67304f27-6ca0-4d47-ba9c-0231219a8358" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_d98c6335-39f4-4815-af22-520c75c07e78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_097ea56d-7433-4d02-b1e7-11e17eec9974" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_c3243c55-987f-4a79-bd4c-b4ba0fa7794f" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_097ea56d-7433-4d02-b1e7-11e17eec9974" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_097ea56d-7433-4d02-b1e7-11e17eec9974_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_097ea56d-7433-4d02-b1e7-11e17eec9974" xlink:to="loc_us-gaap_EquityComponentDomain_097ea56d-7433-4d02-b1e7-11e17eec9974_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_07605b6c-2134-44b9-8aec-83c4e2fad0af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_097ea56d-7433-4d02-b1e7-11e17eec9974" xlink:to="loc_us-gaap_EquityComponentDomain_07605b6c-2134-44b9-8aec-83c4e2fad0af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_4a216300-6667-4e75-9de7-c51a212fb110" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_07605b6c-2134-44b9-8aec-83c4e2fad0af" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_4a216300-6667-4e75-9de7-c51a212fb110" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_b05184f1-94fa-4b47-bcd1-f7b4b55cbc6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_4a216300-6667-4e75-9de7-c51a212fb110" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_b05184f1-94fa-4b47-bcd1-f7b4b55cbc6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_4948488e-13e2-432d-8378-91e3c56f3453" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_4a216300-6667-4e75-9de7-c51a212fb110" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember_4948488e-13e2-432d-8378-91e3c56f3453" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_dcb4b3e8-f33b-4104-8217-37c4e84f7116" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_07605b6c-2134-44b9-8aec-83c4e2fad0af" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_dcb4b3e8-f33b-4104-8217-37c4e84f7116" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_18e92921-05da-4dc4-8db9-78666560eac9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_c3243c55-987f-4a79-bd4c-b4ba0fa7794f" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_18e92921-05da-4dc4-8db9-78666560eac9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_18e92921-05da-4dc4-8db9-78666560eac9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_18e92921-05da-4dc4-8db9-78666560eac9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_18e92921-05da-4dc4-8db9-78666560eac9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_f6147501-8905-49ca-9fd2-d093da3fbe55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_18e92921-05da-4dc4-8db9-78666560eac9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_f6147501-8905-49ca-9fd2-d093da3fbe55" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_4a2e581b-5be1-41c7-85ab-c6e17c30b5b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f6147501-8905-49ca-9fd2-d093da3fbe55" xlink:to="loc_us-gaap_InterestRateSwapMember_4a2e581b-5be1-41c7-85ab-c6e17c30b5b2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_79712c0f-5302-48d8-905a-d43d2b93755e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f6147501-8905-49ca-9fd2-d093da3fbe55" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_79712c0f-5302-48d8-905a-d43d2b93755e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_fb0ea2d8-1984-4a3a-9d32-6801cc7d7506" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_fb0ea2d8-1984-4a3a-9d32-6801cc7d7506" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_57d46dd1-1344-480c-bd99-9f3c0e15a177" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_OtherNonoperatingExpense_57d46dd1-1344-480c-bd99-9f3c0e15a177" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2689232c-4d2a-4ff3-bf27-9337524f435f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2689232c-4d2a-4ff3-bf27-9337524f435f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_0983c9f4-a776-4379-9793-a45fa5ddfc0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_0983c9f4-a776-4379-9793-a45fa5ddfc0d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_de63db82-0a47-45b0-b36d-d21d206bd202" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_InterestExpenseNonoperating_de63db82-0a47-45b0-b36d-d21d206bd202" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_27236f59-96b5-428c-8cb7-6f049fd34d8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_27236f59-96b5-428c-8cb7-6f049fd34d8a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_2c5b2778-3ab5-48c8-98f5-90fe5dec7aef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_ProfitLoss_2c5b2778-3ab5-48c8-98f5-90fe5dec7aef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_f672b754-546a-4000-809c-43463e6333ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_e2b67974-c484-4ba1-97f3-653d32955b58" xlink:to="loc_us-gaap_DerivativeNotionalAmount_f672b754-546a-4000-809c-43463e6333ad" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.kadant.com/role/SubsequentEventDetails" xlink:type="simple" xlink:href="kai-20260103.xsd#SubsequentEventDetails"/>
  <link:definitionLink xlink:role="http://www.kadant.com/role/SubsequentEventDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_518c5959-0442-4828-b6f2-449d83edd489" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_6076d352-0985-459c-b500-3578b49b6241" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_518c5959-0442-4828-b6f2-449d83edd489" xlink:to="loc_us-gaap_SubsequentEventTable_6076d352-0985-459c-b500-3578b49b6241" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_cb25644a-4356-47bf-883e-4568af488ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_6076d352-0985-459c-b500-3578b49b6241" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_cb25644a-4356-47bf-883e-4568af488ab0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_cb25644a-4356-47bf-883e-4568af488ab0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_cb25644a-4356-47bf-883e-4568af488ab0" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_cb25644a-4356-47bf-883e-4568af488ab0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_d4dfb36f-d757-470a-bba1-395c32bb0a32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_cb25644a-4356-47bf-883e-4568af488ab0" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_d4dfb36f-d757-470a-bba1-395c32bb0a32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_169ada2c-b34e-4a47-af92-c6b826519261" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_d4dfb36f-d757-470a-bba1-395c32bb0a32" xlink:to="loc_us-gaap_SubsequentEventMember_169ada2c-b34e-4a47-af92-c6b826519261" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019b8daa-1e5a-7a86-ba5a-a19737361822" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_6076d352-0985-459c-b500-3578b49b6241" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019b8daa-1e5a-7a86-ba5a-a19737361822" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8daa-1e5a-7a86-ba5a-a19737361822_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019b8daa-1e5a-7a86-ba5a-a19737361822" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8daa-1e5a-7a86-ba5a-a19737361822_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8daa-1e5a-7b33-89ce-b6778780581e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019b8daa-1e5a-7a86-ba5a-a19737361822" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8daa-1e5a-7b33-89ce-b6778780581e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_kai_BOHLERProfilGmbHCoKGMember_019bb2d4-b01c-7675-9f17-13cb06ed95aa" xlink:href="kai-20260103.xsd#kai_BOHLERProfilGmbHCoKGMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019b8daa-1e5a-7b33-89ce-b6778780581e" xlink:to="loc_kai_BOHLERProfilGmbHCoKGMember_019bb2d4-b01c-7675-9f17-13cb06ed95aa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_8414e741-0036-4a95-952a-a3d1d9d7618c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_518c5959-0442-4828-b6f2-449d83edd489" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_8414e741-0036-4a95-952a-a3d1d9d7618c" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="101"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:type="arc" order="102"/>
  </link:definitionLink>
</link:linkbase>
