inscrutable (adj.)youdaoicibaDictYouDict[inscrutable 词源字典]
c. 1500, from Late Latin inscrutabilis, from in- "not, opposite of" (see in- (1)) + scrutabilis, from scrutari "examine, ransack" (see scrutiny). Related: Inscrutably.[inscrutable etymology, inscrutable origin, 英语词源]