ringworm

n. any of several contagious fungal skin diseases characterized by itchy ring-shaped patches on the skin

Ringworm, also known as "Tinea", is a contagious fungal infection of the skin, and can exist anywhere on the body. Contrary to its name, ringworm is not caused by a worm, but generally is a reddish to brownish raised or bumpy patch of skin that may be lighter in the center, giving the appearance of a 'ring'.
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Ringworm is a common fungal infection of the skin. The name is a misnomer since the disease is not caused by a worm. [more]Ringworm - Community and Resources

Noun
1. infections of the skin or nails caused by fungi and appearing as itching circular patches
(synonym) tinea, roundworm
(hypernym) fungal infection, mycosis
(hyponym) dhobi itch

n. ringworm