a disease of cereals and other grasses caused by ascomycete fungi of the genus Claviceps, esp C. purpurea, in which the seeds or grain of the plants are replaced by the spore-containing bodies (sclerotia) of the fungus

any fungus causing this disease

the dried sclerotia of C. purpurea, used as the source of certain alkaloids used to treat haemorrhage, facilitate uterine contraction in childbirth, etc