- Noun. (botany) Any of the poisonous plants belonging to the genus ''Solanum'', especially black nightshade or woody nightshade.
- Noun. (botany, colloquial) Any plant of the wider Solanaceae family, including the nightshades as well as tomato, potato, eggplant, and deadly nightshade.
- Noun. Belladonna or deadly nightshade, ''Atropa belladonna''.
- Noun. Any of several plants likened to nightshade, usually because of similar dark-colored berries.