any of various contagious skin diseases caused by related varieties of fungus and characterized by itching and the formation of ring-shaped, discolored patches covered with scales or vesicles
See ringworm in American Heritage Dictionary 4
noun
Any of a number of contagious skin diseases caused by several related fungi, characterized by ring-shaped, scaly, itching patches on the skin and generally classified by its location on the body. Also called tinea.