noun. A crystalline alkaloid, C₃₃H₃₅N₅O₅, derived from ergot that induces vasoconstriction and is used especially in treating migraine.

noun. An alkaloid, extracted from ergot, that causes constriction of blood vessels and has been used to treat migraine; it is related to lysergic acid.

noun. an alkaloid derived from ergot that is less toxic than ergot; causes constriction of blood vessels and is used to treat migraine

"From the ninth to the 19th centuries, Europe suffered a succession of epidemics caused by contamination of rye with ergot, a poisonous mold that produces the potent toxin ergotamine, the consumption of which induces hallucinations, bizarre behavior, and violent muscle twitching."

alkaloid