Source : Webster's Revised Unabridged Dictionary (1913)

Belladonna \Bel`la*don"na\, n. [It., literally fine lady; bella
   beautiful + donna lady.] (Bot.)
   (a) An herbaceous European plant ({Atropa belladonna}) with
       reddish bell-shaped flowers and shining black berries.
       The whole plant and its fruit are very poisonous, and the
       root and leaves are used as powerful medicinal agents.
       Its properties are largely due to the alkaloid atropine
       which it contains. Called also {deadly nightshade}.
   (b) A species of {Amaryllis} ({A. belladonna}); the
       belladonna lily.