n.1 Bot. a poisonous plant, Atropa belladonna, with purple flowers and purple-black berries. Also called deadly nightshade.
2 Med. a drug prepared from this.
Phrases and idioms:
belladonna lily a S. African amaryllis with white or pink flowers, Amaryllis belladonna.
Etymology: mod.L f. It., fair lady, perh. from its use as a cosmetic