irreproachable (adj.)youdaoicibaDictYouDict[irreproachable 词源字典]
1630s, from French irréprochable (15c.), from assimilated form of in- "not, opposite of" (see in- (1)) + réprochable (see reproach). Related: Irreproachably.[irreproachable etymology, irreproachable origin, 英语词源]