Definition of white hellebore in US English:

white hellebore

noun

  • The white-flowered Eurasian herbaceous plant Veratrum album (family Melanthiaceae), the toxic root of which has been used medicinally (especially as a purgative) and as a pesticide; (in later use also) any of various other plants of the genus Veratrum, especially (more fully "American white hellebore") V. viride of North America; frequently attributive.

Origin

Late Middle English; earliest use found in Guy de Chauliac's Grande Chirurgie. After classical Latin elleborus albus (Pliny).