ERGOT

noun Etymology: French, literally, cock's spur Date: 1683 the black or dark purple sclerotium of fungi (genus Claviceps ) that occurs as a club-shaped body replacing the seed of a grass (as rye), a disease of rye and other cereals caused by an ~ fungus, 3. the dried sclerotia of an ~ fungus grown on rye and containing several alkaloids (as ergonovine and ~amine), any of such alkaloids used medicinally for their contractile effect on smooth muscle (as of the uterus and or blood vessels), ~ic adjective