irreligious (adj.)youdaoicibaDictYouDict[irreligious 词源字典]
c. 1400, from Late Latin irreligiosus "irreligious, impious," from assimilated form of in- "not, opposite of" (see in- (1)) + religiosus (see religious). Related: Irreligiously.[irreligious etymology, irreligious origin, 英语词源]