: nevi) is a nonspecific medical term for a visible, circumscribed, chronic lesion of the skin or mucosa.

[1] The term originates from nævus, which is Latin for "birthmark"; however, a nevus can be either congenital (present at birth) or acquired.

[10] These nevi represent excess growth of specific cells types found in the skin, including those that make up oil and sweat glands.

[8] Connective tissue nevi represent abnormalities of collagen in the dermis, the deep layer of the skin.

The ABCDE criteria (asymmetry, border irregularity, color variegation, diameter > 6 mm, and evolution) are often used to distinguish nevi from melanomas in adults, while modified criteria (amelanosis, bleeding or bumps, uniform color, small diameter or de novo, and evolution) can be used when evaluating suspicious lesions in children.