one of two forms that coelenterates take e.g. a hydra or coral: usually sedentary and has a hollow cylindrical body usually with a ring of tentacles around the mouth
a small vascular growth on the surface of a mucous membrane
a widespread outbreak of an infectious disease; many people are infected at the same time
(especially of medicine) of disease or anything resembling a disease; attacking or affecting many individuals in a community or a population simultaneously; "an epidemic outbreak of influenza"