illegal (adj.)youdaoicibaDictYouDict[illegal 词源字典]
1620s, from French illégal or directly from Medieval Latin illegalis, from assimilated form of in- "not, opposite of" (see in- (1)) + Latin legalis (see legal). Term illegal immigrant first recorded 1892 in American English (illegal immigration is from 1887).[illegal etymology, illegal origin, 英语词源]