<?xml version="1.0" encoding="us-ascii"?>
<!-- XBRL document created with Praxa -->
<!-- Copyright (c) 2026 Praxa LLC. All Rights Reserved.-->
<!-- Creation Date: 2026-08-12T20:30:15.1887+00:00 -->
<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:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/InterimCondensedConsolidatedStatementsofShareholdersEquityUnaudited" xlink:href="pypd-20260630.xsd#InterimCondensedConsolidatedStatementsofShareholdersEquityUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/ShareholdersEquityScheduleofOptionstoEmployeesUndertheCompanysOptionPlanDetails" xlink:href="pypd-20260630.xsd#ShareholdersEquityScheduleofOptionstoEmployeesUndertheCompanysOptionPlanDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/ShareholdersEquityDetails" xlink:href="pypd-20260630.xsd#ShareholdersEquityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/SubsequentEventsDetails" xlink:href="pypd-20260630.xsd#SubsequentEventsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/ShareholdersEquityScheduleofWarrantsExercisableIntoOrdinarySharesDetails" xlink:href="pypd-20260630.xsd#ShareholdersEquityScheduleofWarrantsExercisableIntoOrdinarySharesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/CommitmentsandContingentLiabilitiesDetails" xlink:href="pypd-20260630.xsd#CommitmentsandContingentLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/ShareholdersEquityScheduleofShareBasedCompensationExpenseDetails" xlink:href="pypd-20260630.xsd#ShareholdersEquityScheduleofShareBasedCompensationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://polypid.com/20260630/role/BasicandDilutedNetLossPerShareScheduleofDilutedNetLossPerShareAttributabletoShareholdersDetails" xlink:href="pypd-20260630.xsd#BasicandDilutedNetLossPerShareScheduleofDilutedNetLossPerShareAttributabletoShareholdersDetails" xlink:type="simple" />
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/InterimCondensedConsolidatedStatementsofShareholdersEquityUnaudited" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember_1064" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember_1969" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember_1065" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis_1062" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_1066" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity_1068" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1070" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_1089" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss_1091" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding_1093" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1090" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable_1061" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems_1067" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StockIssuedDuringPeriodValueIssuanceofOrdinarySharesAbeyanceSharesandWarrantsNet" xlink:label="pypd_StockIssuedDuringPeriodValueIssuanceofOrdinarySharesAbeyanceSharesandWarrantsNet_1071" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StockIssuedDuringPeriodValueExerciseOfPrefundedWarrants" xlink:label="pypd_StockIssuedDuringPeriodValueExerciseOfPrefundedWarrants_1073" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StockIssuedDuringPeriodSharesIssuanceofOrdinarySharesAbeyanceSharesandWarrantsNet" xlink:label="pypd_StockIssuedDuringPeriodSharesIssuanceofOrdinarySharesAbeyanceSharesandWarrantsNet_1072" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StockIssueDuringPeriodSharesExerciseOfPrefundedWarrants" xlink:label="pypd_StockIssueDuringPeriodSharesExerciseOfPrefundedWarrants_1074" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_1066_default" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain_1066" xlink:to="us-gaap_AdditionalPaidInCapitalMember_1064" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain_1066" xlink:to="us-gaap_CommonStockMember_1969" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain_1066" xlink:to="us-gaap_RetainedEarningsMember_1065" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_StatementTable_1061" xlink:to="us-gaap_StatementEquityComponentsAxis_1062" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis_1062" xlink:to="us-gaap_EquityComponentDomain_1066" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="us-gaap_StockholdersEquity_1068" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_1070" />
    <link:definitionArc xlink:type="arc" order="31.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_1089" />
    <link:definitionArc xlink:type="arc" order="33.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="us-gaap_NetIncomeLoss_1091" />
    <link:definitionArc xlink:type="arc" order="35.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="us-gaap_CommonStockSharesOutstanding_1093" />
    <link:definitionArc xlink:type="arc" order="32.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1090" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="us-gaap_StatementTable_1061" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="pypd_StockIssuedDuringPeriodValueIssuanceofOrdinarySharesAbeyanceSharesandWarrantsNet_1071" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="pypd_StockIssuedDuringPeriodValueExerciseOfPrefundedWarrants_1073" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="pypd_StockIssuedDuringPeriodSharesIssuanceofOrdinarySharesAbeyanceSharesandWarrantsNet_1072" />
    <link:definitionArc xlink:type="arc" order="16.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_StatementLineItems_1067" xlink:to="pypd_StockIssueDuringPeriodSharesExerciseOfPrefundedWarrants_1074" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis_1062" xlink:to="us-gaap_EquityComponentDomain_1066_default" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/ShareholdersEquityScheduleofOptionstoEmployeesUndertheCompanysOptionPlanDetails" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_EmployeesAndNonEmployeesMember" xlink:label="pypd_EmployeesAndNonEmployeesMember_1346" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ShareholdersEquityScheduleofOptionstoEmployeesUndertheCompanysOptionPlanDetailsTable" xlink:label="pypd_ShareholdersEquityScheduleofOptionstoEmployeesUndertheCompanysOptionPlanDetailsTable_1344" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_1348" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_1350" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="us-gaap_RelatedPartyDomain_1965" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_1990" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_1991" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_1355" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_1357" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_1364" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_1366" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_1359" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_1361" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_1363" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_1352" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_1354" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_1356" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_1358" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_1365" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_1367" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1360" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1362" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1345" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_1353" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_1368" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="us-gaap_RelatedPartyDomain_1965_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_RelatedPartyDomain_1965" xlink:to="pypd_EmployeesAndNonEmployeesMember_1346" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="pypd_ShareholdersEquityScheduleofOptionstoEmployeesUndertheCompanysOptionPlanDetailsTable_1344" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_1348" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_1350" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1345" xlink:to="us-gaap_RelatedPartyDomain_1965" />
    <link:definitionArc xlink:type="arc" order="24.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_1990" />
    <link:definitionArc xlink:type="arc" order="26.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_1991" />
    <link:definitionArc xlink:type="arc" order="30.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_1355" />
    <link:definitionArc xlink:type="arc" order="32.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice_1357" />
    <link:definitionArc xlink:type="arc" order="18.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_1364" />
    <link:definitionArc xlink:type="arc" order="20.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_1366" />
    <link:definitionArc xlink:type="arc" order="34.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_1359" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_1361" />
    <link:definitionArc xlink:type="arc" order="17.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_1363" />
    <link:definitionArc xlink:type="arc" order="27.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_1352" />
    <link:definitionArc xlink:type="arc" order="29.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_1354" />
    <link:definitionArc xlink:type="arc" order="31.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_1356" />
    <link:definitionArc xlink:type="arc" order="33.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_1358" />
    <link:definitionArc xlink:type="arc" order="19.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_1365" />
    <link:definitionArc xlink:type="arc" order="21.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_1367" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1360" />
    <link:definitionArc xlink:type="arc" order="16.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_1362" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityScheduleofOptionstoEmployeesUndertheCompanysOptionPlanDetailsTable_1344" xlink:to="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1345" />
    <link:definitionArc xlink:type="arc" order="28.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_1353" />
    <link:definitionArc xlink:type="arc" order="22.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1347" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_1368" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_1345" xlink:to="us-gaap_RelatedPartyDomain_1965_default" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/SubsequentEventsDetails" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_August2024Member" xlink:label="pypd_August2024Member_1667" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_NewDrugApplicationMember" xlink:label="pypd_NewDrugApplicationMember_1978" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember" xlink:label="us-gaap_SubsequentEventMember_1661" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioForecastMember" xlink:label="srt_ScenarioForecastMember_2001" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember" xlink:label="us-gaap_WarrantMember_2002" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="srt_RangeMember_2004" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_2005" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember_2006" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain_1967" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="us-gaap_SubsequentEventTypeAxis_1660" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_1669" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateAxis" xlink:label="us-gaap_AwardDateAxis_1662" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfStockIssuanceCosts" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts_1674" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="us-gaap_ProceedsFromWarrantExercises_1676" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems" xlink:label="us-gaap_SubsequentEventLineItems_1671" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_1673" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_AmountOfUpfrontPayment" xlink:label="pypd_AmountOfUpfrontPayment_1970" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_MilestonePaymentsReceivable" xlink:label="pypd_MilestonePaymentsReceivable_1974" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis_1976" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1977" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_SubsequentEventsDetailsTable" xlink:label="pypd_SubsequentEventsDetailsTable_1659" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="us-gaap_ClassOfWarrantOrRightAxis_1668" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateDomain" xlink:label="us-gaap_AwardDateDomain_1663" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_WarrantsExercise" xlink:label="pypd_WarrantsExercise_1675" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis" xlink:label="srt_StatementScenarioAxis_1999" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain_2000" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_2003" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="srt_RangeMember_2004_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain_1967_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_1669_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1977_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateDomain" xlink:label="us-gaap_AwardDateDomain_1663_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain_2000_default" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain_1663" xlink:to="pypd_August2024Member_1667" />
    <link:definitionArc xlink:type="arc" order="125.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1977" xlink:to="pypd_NewDrugApplicationMember_1978" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventTypeDomain_1967" xlink:to="us-gaap_SubsequentEventMember_1661" />
    <link:definitionArc xlink:type="arc" order="134.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_ScenarioUnspecifiedDomain_2000" xlink:to="srt_ScenarioForecastMember_2001" />
    <link:definitionArc xlink:type="arc" order="135.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1669" xlink:to="us-gaap_WarrantMember_2002" />
    <link:definitionArc xlink:type="arc" order="137.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis_2003" xlink:to="srt_RangeMember_2004" />
    <link:definitionArc xlink:type="arc" order="138.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember_2004" xlink:to="srt_MaximumMember_2005" />
    <link:definitionArc xlink:type="arc" order="139.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember_2004" xlink:to="srt_MinimumMember_2006" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsequentEventTypeAxis_1660" xlink:to="us-gaap_SubsequentEventTypeDomain_1967" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_SubsequentEventsDetailsTable_1659" xlink:to="us-gaap_SubsequentEventTypeAxis_1660" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis_1668" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_1669" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_SubsequentEventsDetailsTable_1659" xlink:to="us-gaap_AwardDateAxis_1662" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems_1671" xlink:to="us-gaap_PaymentsOfStockIssuanceCosts_1674" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems_1671" xlink:to="us-gaap_ProceedsFromWarrantExercises_1676" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems_1671" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues_1673" />
    <link:definitionArc xlink:type="arc" order="19.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems_1671" xlink:to="pypd_AmountOfUpfrontPayment_1970" />
    <link:definitionArc xlink:type="arc" order="20.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems_1671" xlink:to="pypd_MilestonePaymentsReceivable_1974" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_SubsequentEventsDetailsTable_1659" xlink:to="us-gaap_AwardTypeAxis_1976" />
    <link:definitionArc xlink:type="arc" order="124.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis_1976" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1977" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_SubsequentEventLineItems_1671" xlink:to="pypd_SubsequentEventsDetailsTable_1659" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_SubsequentEventsDetailsTable_1659" xlink:to="us-gaap_ClassOfWarrantOrRightAxis_1668" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardDateAxis_1662" xlink:to="us-gaap_AwardDateDomain_1663" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SubsequentEventLineItems_1671" xlink:to="pypd_WarrantsExercise_1675" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_SubsequentEventsDetailsTable_1659" xlink:to="srt_StatementScenarioAxis_1999" />
    <link:definitionArc xlink:type="arc" order="133.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_StatementScenarioAxis_1999" xlink:to="srt_ScenarioUnspecifiedDomain_2000" />
    <link:definitionArc xlink:type="arc" order="16.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_SubsequentEventsDetailsTable_1659" xlink:to="srt_RangeAxis_2003" />
    <link:definitionArc xlink:type="arc" order="137.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis_2003" xlink:to="srt_RangeMember_2004_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsequentEventTypeAxis_1660" xlink:to="us-gaap_SubsequentEventTypeDomain_1967_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ClassOfWarrantOrRightAxis_1668" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_1669_default" />
    <link:definitionArc xlink:type="arc" order="124.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardTypeAxis_1976" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1977_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardDateAxis_1662" xlink:to="us-gaap_AwardDateDomain_1663_default" />
    <link:definitionArc xlink:type="arc" order="133.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_StatementScenarioAxis_1999" xlink:to="srt_ScenarioUnspecifiedDomain_2000_default" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/ShareholdersEquityDetails" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockOptionMember" xlink:label="us-gaap_StockOptionMember_1597" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_1599" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrivatePlacementMember" xlink:label="us-gaap_PrivatePlacementMember_1586" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember_1603" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_AbeyanceMember" xlink:label="pypd_AbeyanceMember_1612" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_January2024WarrantsMember" xlink:label="pypd_January2024WarrantsMember_1616" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_August2024WarrantsMember" xlink:label="pypd_August2024WarrantsMember_1618" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_NewWarrantsMember" xlink:label="pypd_NewWarrantsMember_1620" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_InducementLetterMember" xlink:label="pypd_InducementLetterMember_1600" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IPOMember" xlink:label="us-gaap_IPOMember_1587" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember_1590" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_PreFundedWarrantsMember" xlink:label="pypd_PreFundedWarrantsMember_1594" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_PreFundedWarrantsMember" xlink:label="pypd_PreFundedWarrantsMember_1615" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember" xlink:label="us-gaap_WarrantMember_1617" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_December2024WarrantsMember" xlink:label="pypd_December2024WarrantsMember_1619" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_NewWarrantsSharesMember" xlink:label="pypd_NewWarrantsSharesMember_1621" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_OfficersMember" xlink:label="pypd_OfficersMember_1606" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="srt_RangeMember_1589" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember_1591" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_DefinitiveSecuritiesPurchaseAgreementMember" xlink:label="pypd_DefinitiveSecuritiesPurchaseAgreementMember_1611" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis_1601" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis_1588" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="us-gaap_ClassOfWarrantOrRightAxis_1613" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_FairValueOfWarrantPricePerShare" xlink:label="pypd_FairValueOfWarrantPricePerShare_1636" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ProceedsToIssuanceCostNetAmount" xlink:label="pypd_ProceedsToIssuanceCostNetAmount_1638" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightUnissued" xlink:label="us-gaap_ClassOfWarrantOrRightUnissued_1640" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1652" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_UnrecognizedCompensationCosts" xlink:label="pypd_UnrecognizedCompensationCosts_1654" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_1630" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstandingTerm" xlink:label="us-gaap_WarrantsAndRightsOutstandingTerm_1632" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromDebtNetOfIssuanceCosts" xlink:label="us-gaap_ProceedsFromDebtNetOfIssuanceCosts_1634" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding_1980" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_1981" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockLineItems" xlink:label="us-gaap_ClassOfStockLineItems_1622" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredOfferingCosts" xlink:label="us-gaap_DeferredOfferingCosts_1624" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_1605" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StockOptionVestingPeriodDescription" xlink:label="pypd_StockOptionVestingPeriodDescription_1645" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_RecognizedWeightedAveragePeriod" xlink:label="pypd_RecognizedWeightedAveragePeriod_1655" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_1585" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ShareholdersEquityDetailsTable" xlink:label="pypd_ShareholdersEquityDetailsTable_1583" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis_1592" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1596" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis_1598" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction" xlink:label="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_1625" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1610" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1644" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="us-gaap_ProceedsFromIssuanceOrSaleOfEquity_1642" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis" xlink:label="us-gaap_SubsidiarySaleOfStockAxis_1584" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain_1593" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis" xlink:label="us-gaap_AwardTypeAxis_1595" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockPricePerShare" xlink:label="us-gaap_SaleOfStockPricePerShare_1629" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1631" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_1633" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="us-gaap_ProceedsFromWarrantExercises_1635" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_1602" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="srt_TitleOfIndividualAxis_1604" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_1614" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="dei_LegalEntityAxis_1609" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock_1626" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_1628" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="us-gaap_StockIssuedDuringPeriodSharesOther_1637" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantExercisePriceIncrease" xlink:label="us-gaap_WarrantExercisePriceIncrease_1639" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceInitialPublicOffering" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_1641" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockVotingRights" xlink:label="us-gaap_CommonStockVotingRights_1643" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_1599_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="srt_RangeMember_1589_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_1605_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain" xlink:label="us-gaap_SaleOfStockNameOfTransactionDomain_1585_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1596_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain_1610_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain_1593_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_1602_default" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_1614_default" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1596" xlink:to="us-gaap_StockOptionMember_1597" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_TypeOfArrangementAxis_1598" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember_1599" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain_1585" xlink:to="us-gaap_PrivatePlacementMember_1586" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EquityComponentDomain_1602" xlink:to="us-gaap_CommonStockMember_1603" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain_1610" xlink:to="pypd_AbeyanceMember_1612" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1614" xlink:to="pypd_January2024WarrantsMember_1616" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1614" xlink:to="pypd_August2024WarrantsMember_1618" />
    <link:definitionArc xlink:type="arc" order="16.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1614" xlink:to="pypd_NewWarrantsMember_1620" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember_1599" xlink:to="pypd_InducementLetterMember_1600" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_SaleOfStockNameOfTransactionDomain_1585" xlink:to="us-gaap_IPOMember_1587" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember_1589" xlink:to="srt_MaximumMember_1590" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockDomain_1593" xlink:to="pypd_PreFundedWarrantsMember_1594" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1614" xlink:to="pypd_PreFundedWarrantsMember_1615" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1614" xlink:to="us-gaap_WarrantMember_1617" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1614" xlink:to="pypd_December2024WarrantsMember_1619" />
    <link:definitionArc xlink:type="arc" order="17.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightDomain_1614" xlink:to="pypd_NewWarrantsSharesMember_1621" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain_1605" xlink:to="pypd_OfficersMember_1606" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_RangeAxis_1588" xlink:to="srt_RangeMember_1589" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_RangeMember_1589" xlink:to="srt_MinimumMember_1591" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain_1610" xlink:to="pypd_DefinitiveSecuritiesPurchaseAgreementMember_1611" />
    <link:definitionArc xlink:type="arc" order="16.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="us-gaap_StatementEquityComponentsAxis_1601" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="srt_RangeAxis_1588" />
    <link:definitionArc xlink:type="arc" order="19.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="us-gaap_ClassOfWarrantOrRightAxis_1613" />
    <link:definitionArc xlink:type="arc" order="23.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="pypd_FairValueOfWarrantPricePerShare_1636" />
    <link:definitionArc xlink:type="arc" order="25.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="pypd_ProceedsToIssuanceCostNetAmount_1638" />
    <link:definitionArc xlink:type="arc" order="27.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ClassOfWarrantOrRightUnissued_1640" />
    <link:definitionArc xlink:type="arc" order="39.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_1652" />
    <link:definitionArc xlink:type="arc" order="41.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="pypd_UnrecognizedCompensationCosts_1654" />
    <link:definitionArc xlink:type="arc" order="17.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_1630" />
    <link:definitionArc xlink:type="arc" order="19.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_WarrantsAndRightsOutstandingTerm_1632" />
    <link:definitionArc xlink:type="arc" order="21.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ProceedsFromDebtNetOfIssuanceCosts_1634" />
    <link:definitionArc xlink:type="arc" order="44.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding_1980" />
    <link:definitionArc xlink:type="arc" order="127.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_1981" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_DeferredOfferingCosts_1624" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_TitleOfIndividualAxis_1604" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_1605" />
    <link:definitionArc xlink:type="arc" order="32.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="pypd_StockOptionVestingPeriodDescription_1645" />
    <link:definitionArc xlink:type="arc" order="42.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="pypd_RecognizedWeightedAveragePeriod_1655" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_SubsidiarySaleOfStockAxis_1584" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain_1585" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="pypd_ShareholdersEquityDetailsTable_1583" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="us-gaap_StatementClassOfStockAxis_1592" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardTypeAxis_1595" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1596" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="us-gaap_TypeOfArrangementAxis_1598" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_1625" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="dei_LegalEntityAxis_1609" xlink:to="dei_EntityDomain_1610" />
    <link:definitionArc xlink:type="arc" order="31.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_1644" />
    <link:definitionArc xlink:type="arc" order="29.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ProceedsFromIssuanceOrSaleOfEquity_1642" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="us-gaap_SubsidiarySaleOfStockAxis_1584" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementClassOfStockAxis_1592" xlink:to="us-gaap_ClassOfStockDomain_1593" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="us-gaap_AwardTypeAxis_1595" />
    <link:definitionArc xlink:type="arc" order="16.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_SaleOfStockPricePerShare_1629" />
    <link:definitionArc xlink:type="arc" order="18.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1631" />
    <link:definitionArc xlink:type="arc" order="20.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_1633" />
    <link:definitionArc xlink:type="arc" order="22.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ProceedsFromWarrantExercises_1635" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_StatementEquityComponentsAxis_1601" xlink:to="us-gaap_EquityComponentDomain_1602" />
    <link:definitionArc xlink:type="arc" order="17.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="srt_TitleOfIndividualAxis_1604" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_ClassOfWarrantOrRightAxis_1613" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_1614" />
    <link:definitionArc xlink:type="arc" order="18.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_ShareholdersEquityDetailsTable_1583" xlink:to="dei_LegalEntityAxis_1609" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock_1626" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues_1628" />
    <link:definitionArc xlink:type="arc" order="24.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_StockIssuedDuringPeriodSharesOther_1637" />
    <link:definitionArc xlink:type="arc" order="26.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_WarrantExercisePriceIncrease_1639" />
    <link:definitionArc xlink:type="arc" order="28.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_ProceedsFromIssuanceInitialPublicOffering_1641" />
    <link:definitionArc xlink:type="arc" order="30.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfStockLineItems_1622" xlink:to="us-gaap_CommonStockVotingRights_1643" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_TypeOfArrangementAxis_1598" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember_1599_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_RangeAxis_1588" xlink:to="srt_RangeMember_1589_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_TitleOfIndividualAxis_1604" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_1605_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_SubsidiarySaleOfStockAxis_1584" xlink:to="us-gaap_SaleOfStockNameOfTransactionDomain_1585_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardTypeAxis_1595" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1596_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="dei_LegalEntityAxis_1609" xlink:to="dei_EntityDomain_1610_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementClassOfStockAxis_1592" xlink:to="us-gaap_ClassOfStockDomain_1593_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_StatementEquityComponentsAxis_1601" xlink:to="us-gaap_EquityComponentDomain_1602_default" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_ClassOfWarrantOrRightAxis_1613" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_1614_default" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/CommitmentsandContingentLiabilitiesDetails" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ResearchAndDevelopmentExpensesMember" xlink:label="pypd_ResearchAndDevelopmentExpensesMember_1985" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_IsraelInnovationAuthorityOfTheMinistryOfEconomyMember" xlink:label="pypd_IsraelInnovationAuthorityOfTheMinistryOfEconomyMember_1553" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_CommitmentsandContingentLiabilitiesDetailsTable" xlink:label="pypd_CommitmentsandContingentLiabilitiesDetailsTable_1550" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_1552" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StatementOfIncomeLocationAxis" xlink:label="pypd_StatementOfIncomeLocationAxis_1983" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StatementOfIncomeLocationDomain" xlink:label="pypd_StatementOfIncomeLocationDomain_1984" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsLineItems" xlink:label="us-gaap_OtherCommitmentsLineItems_1557" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_PercentageOfRoyaltiesRateOfSales" xlink:label="pypd_PercentageOfRoyaltiesRateOfSales_1559" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidRoyalties" xlink:label="us-gaap_PrepaidRoyalties_1561" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="srt_TitleOfIndividualAxis_1551" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ProceedsFromParticipationPayments" xlink:label="pypd_ProceedsFromParticipationPayments_1558" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_PercentageOfGrantReceived" xlink:label="pypd_PercentageOfGrantReceived_1560" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedRoyaltiesCurrent" xlink:label="us-gaap_AccruedRoyaltiesCurrent_1562" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_1552_default" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StatementOfIncomeLocationDomain" xlink:label="pypd_StatementOfIncomeLocationDomain_1984_default" />
    <link:definitionArc xlink:type="arc" order="131.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="pypd_StatementOfIncomeLocationDomain_1984" xlink:to="pypd_ResearchAndDevelopmentExpensesMember_1985" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain_1552" xlink:to="pypd_IsraelInnovationAuthorityOfTheMinistryOfEconomyMember_1553" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_OtherCommitmentsLineItems_1557" xlink:to="pypd_CommitmentsandContingentLiabilitiesDetailsTable_1550" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="srt_TitleOfIndividualAxis_1551" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_1552" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_CommitmentsandContingentLiabilitiesDetailsTable_1550" xlink:to="pypd_StatementOfIncomeLocationAxis_1983" />
    <link:definitionArc xlink:type="arc" order="130.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="pypd_StatementOfIncomeLocationAxis_1983" xlink:to="pypd_StatementOfIncomeLocationDomain_1984" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherCommitmentsLineItems_1557" xlink:to="pypd_PercentageOfRoyaltiesRateOfSales_1559" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherCommitmentsLineItems_1557" xlink:to="us-gaap_PrepaidRoyalties_1561" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="pypd_CommitmentsandContingentLiabilitiesDetailsTable_1550" xlink:to="srt_TitleOfIndividualAxis_1551" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherCommitmentsLineItems_1557" xlink:to="pypd_ProceedsFromParticipationPayments_1558" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherCommitmentsLineItems_1557" xlink:to="pypd_PercentageOfGrantReceived_1560" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_OtherCommitmentsLineItems_1557" xlink:to="us-gaap_AccruedRoyaltiesCurrent_1562" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="srt_TitleOfIndividualAxis_1551" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_1552_default" />
    <link:definitionArc xlink:type="arc" order="130.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="pypd_StatementOfIncomeLocationAxis_1983" xlink:to="pypd_StatementOfIncomeLocationDomain_1984_default" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/ShareholdersEquityScheduleofShareBasedCompensationExpenseDetails" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_MarketingAndBusinessDevelopmentMember" xlink:label="pypd_MarketingAndBusinessDevelopmentMember_1996" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_GeneralAndAdministrativeMember" xlink:label="pypd_GeneralAndAdministrativeMember_1997" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ResearchAndDevelopmentExpensesMember" xlink:label="pypd_ResearchAndDevelopmentExpensesMember_1998" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StatementOfIncomeLocationAxis" xlink:label="pypd_StatementOfIncomeLocationAxis_1993" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StatementOfIncomeLocationDomain" xlink:label="pypd_StatementOfIncomeLocationDomain_1994" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_1377" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense_1378" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1371" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_StatementOfIncomeLocationDomain" xlink:label="pypd_StatementOfIncomeLocationDomain_1994_default" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="pypd_StatementOfIncomeLocationDomain_1994" xlink:to="pypd_MarketingAndBusinessDevelopmentMember_1996" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="pypd_StatementOfIncomeLocationDomain_1994" xlink:to="pypd_GeneralAndAdministrativeMember_1997" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="pypd_StatementOfIncomeLocationDomain_1994" xlink:to="pypd_ResearchAndDevelopmentExpensesMember_1998" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1371" xlink:to="pypd_StatementOfIncomeLocationAxis_1993" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="pypd_StatementOfIncomeLocationAxis_1993" xlink:to="pypd_StatementOfIncomeLocationDomain_1994" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_1377" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense_1378" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_1377" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_1371" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="true" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="pypd_StatementOfIncomeLocationAxis_1993" xlink:to="pypd_StatementOfIncomeLocationDomain_1994_default" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/ShareholdersEquityScheduleofWarrantsExercisableIntoOrdinarySharesDetails" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_July2022Member" xlink:label="pypd_July2022Member_1385" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_August2024Member" xlink:label="pypd_August2024Member_1387" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_April2022OneMember" xlink:label="pypd_April2022OneMember_1975" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_June2025Member" xlink:label="pypd_June2025Member_1388" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_April2022Member" xlink:label="pypd_April2022Member_1384" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateDomain" xlink:label="us-gaap_AwardDateDomain_1383" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="us-gaap_ClassOfWarrantOrRightOutstanding_1393" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber" xlink:label="pypd_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber_1395" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightTable" xlink:label="us-gaap_ClassOfWarrantOrRightTable_1381" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightLineItems" xlink:label="us-gaap_ClassOfWarrantOrRightLineItems_1392" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1394" />
    <link:loc xlink:type="locator" xlink:href="pypd-20260630.xsd#pypd_ShareBasedCompensationArrangementExercisableDate" xlink:label="pypd_ShareBasedCompensationArrangementExercisableDate_1396" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateAxis" xlink:label="us-gaap_AwardDateAxis_1382" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardDateDomain" xlink:label="us-gaap_AwardDateDomain_1383_default" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain_1383" xlink:to="pypd_July2022Member_1385" />
    <link:definitionArc xlink:type="arc" order="14.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain_1383" xlink:to="pypd_August2024Member_1387" />
    <link:definitionArc xlink:type="arc" order="16.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain_1383" xlink:to="pypd_April2022OneMember_1975" />
    <link:definitionArc xlink:type="arc" order="15.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain_1383" xlink:to="pypd_June2025Member_1388" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AwardDateDomain_1383" xlink:to="pypd_April2022Member_1384" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AwardDateAxis_1382" xlink:to="us-gaap_AwardDateDomain_1383" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems_1392" xlink:to="us-gaap_ClassOfWarrantOrRightOutstanding_1393" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems_1392" xlink:to="pypd_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableNumber_1395" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems_1392" xlink:to="us-gaap_ClassOfWarrantOrRightTable_1381" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems_1392" xlink:to="us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_1394" />
    <link:definitionArc xlink:type="arc" order="13.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_ClassOfWarrantOrRightLineItems_1392" xlink:to="pypd_ShareBasedCompensationArrangementExercisableDate_1396" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ClassOfWarrantOrRightTable_1381" xlink:to="us-gaap_AwardDateAxis_1382" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AwardDateAxis_1382" xlink:to="us-gaap_AwardDateDomain_1383_default" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://polypid.com/20260630/role/BasicandDilutedNetLossPerShareScheduleofDilutedNetLossPerShareAttributabletoShareholdersDetails" xlink:type="extended" xlink:title="definitionLink">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember" xlink:label="us-gaap_WarrantMember_1417" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockOptionMember" xlink:label="us-gaap_StockOptionMember_1416" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1414" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1413" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_1415" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1419" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDilutedLineItems" xlink:label="us-gaap_EarningsPerShareDilutedLineItems_1418" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="us-gaap_AntidilutiveSecuritiesNameDomain_1415_default" />
    <link:definitionArc xlink:type="arc" order="12.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain_1415" xlink:to="us-gaap_WarrantMember_1417" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_AntidilutiveSecuritiesNameDomain_1415" xlink:to="us-gaap_StockOptionMember_1416" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1413" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1414" />
    <link:definitionArc xlink:type="arc" order="11.00000" priority="1" xbrldt:closed="true" use="optional" xbrldt:contextElement="segment" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="us-gaap_EarningsPerShareDilutedLineItems_1418" xlink:to="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_1413" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1414" xlink:to="us-gaap_AntidilutiveSecuritiesNameDomain_1415" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="us-gaap_EarningsPerShareDilutedLineItems_1418" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_1419" />
    <link:definitionArc xlink:type="arc" order="10.00000" priority="1" xbrldt:closed="false" use="optional" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_1414" xlink:to="us-gaap_AntidilutiveSecuritiesNameDomain_1415_default" />
  </link:definitionLink>
</link:linkbase>
