clandestine (adj.)youdaoicibaDictYouDict[clandestine 词源字典]
1560s, from Latin clandestinus "secret, hidden," from clam "secretly," from adverbial derivative of base of celare "to hide" (see cell), perhaps on model of intestinus "internal." Related: Clandestinely. As a noun form, there is awkward clandestinity (clandestineness apparently being a dictionary word).[clandestine etymology, clandestine origin, 英语词源]