1. fungus attacking cereals: a disease of cereals caused by the parasitic fungus Claviceps purpurea that grows in dense black masses sclerotia in the grains of the ear
2. fungal bodies used in medicine: the dried sclerotia of an ergot fungus containing physiologically active substances. Use: treatment of migraines, initiation of labor in pregnancy.
[Late 17th century. < French, "rooster's spur"; from the appearance of the diseased grain]
