noun

1. any of a genus (Helleborus) of poisonous, winter-blooming plants of the buttercup family, with buttercuplike flowers of various colors: the rhizomes of a black European species (H. niger) were formerly used as a heart stimulant and cathartic
2. any of a genus (Veratrum) of poisonous plants of the lily family: the white hellebore (V. album) and the false hellebore (V. viride) were formerly used as cathartics, etc.

Etymology: altered (after Gr) < ME ellebore < OFr < L helleborus < Gr helleboros, orig. prob. “plant eaten by fawns” < hellos, var. of ellos, fawn < base of elaphos, deer + bora, food (of beasts): for IE base see elk & voracious