Open English Wordnet
Nouns
(n)rue, herb of grace, Ruta graveolensEuropean strong-scented perennial herb with grey-green bitter-tasting leaves; an irritant similar to poison ivy
(n)sorrow, regret, rue, ruefulnesssadness associated with some wrong done or some disappointment“he drank to drown his sorrows”, “he wrote a note expressing his regret”, “to his rue, the error cost him the game”