Real Dictionary

bittersweet
adjective: If you describe an experience as bittersweet, you mean that it has some happy aspects and some sad ones.

bittersweet in American English
a North American twining woody vine (Celastrus scandens) of the staff-tree family, with poisonous leaves, and bearing clusters of small orange fruits with bright-red fleshy seeds
both bitter and sweet, as dark chocolate made with little sugar
adjective: both bitter and sweet to the taste
noun: a climbing or trailing plant, Solanum dulcamara, of the nightshade family, having small, violet, star-shaped flowers with a protruding yellow center and scarlet berries

bittersweet in British English
noun: any of several North American woody climbing plants of the genus Celastrus, esp C. scandens, having orange capsules that open to expose scarlet-coated seeds: family Celastraceae