bittersweet (n.)youdaoicibaDictYouDict[bittersweet 词源字典]
also bitter-sweet, late 14c., used especially in Middle English in reference to a type of apple, from bitter (adj.) + sweet (adj.). As an adjective, attested from 1610s. Greek had a similarly formed compound, glykypikros, literally "sweet-bitter."[bittersweet etymology, bittersweet origin, 英语词源]