bittersweet (adj.)

"uniting bitterness and sweetness," 1610s, from bitter (adj.) + sweet (adj.). Perhaps older, as the same word is used as a noun in Middle English (late 14c.) for drinks or experiences that are both bitter and sweet and especially in reference to a type of apple; later of woody nightshade (1560s). Greek had a similarly formed compound, glykypikros, literally "sweet-bitter."