infirmity (n.)youdaoicibaDictYouDict[infirmity 词源字典]
late 14c., "disease, sickness; lack of capability, weakness," from Latin infirmitatem (nominative infirmitas) "want of strength, weakness, feebleness," noun of quality from infirmus (see infirm). Perhaps in part from Middle French infirmité, Old French enfermete.[infirmity etymology, infirmity origin, 英语词源]