Nevus: A pigmented spot on the skin, such as a mole. The plural of nevus is nevi. QUESTION Ringworm is caused by a fungus. See Answer From Skin Problems and Treatments Resources Skin Care for PsoriasisIs Your Skin Trouble Blocked Hair Follicles?How Psoriasis Affected An Actress' Career Featured Centers Good and Bad Foods for PsoriasisVideo: Getting Personal on Life With MS Health Solutions From Our Sponsors Shot-Free MS Treatment Your Child and COVID-19