The Collaborative International Dictionary
Helleborein
Helleborein \Hel`le*bo"re*in\, n. (Chem.) A poisonous glucoside accompanying helleborin in several species of hellebore, and extracted as a white crystalline substance with a bittersweet taste. It has a strong action on the heart, resembling digitalin.
Wiktionary
helleborein
n. (alternative form of helleborin English)