deadly : Idioms & Phrases

• noun perennial Eurasian herb with reddish bell-shaped flowers and shining black berries; extensively grown in United States; roots and leaves yield atropine
  belladonna; belladonna plant; Atropa belladonna.
  
• noun poisonous perennial Old World vine having violet flowers and oval coral-red berries; widespread weed in North America
  bittersweet; bittersweet nightshade; climbing nightshade; poisonous nightshade; woody nightshade; Solanum dulcamara.
  

WordNet

• (Bot.), a poisonous plant; belladonna. See under Nightshade.

Webster 1913

• noun an unpardonable sin entailing a total loss of grace
  mortal sin.
  
  • theologians list seven mortal sins

WordNet