naevusPronunciation: /ˈniːvəs/ (US nevus)Definition of naevus noun (plural naevi /-vʌɪ, -viː/) a birthmark or a mole on the skin, especially a birthmark in the form of a raised red patch. Origin: mid 19th century: from Latinnaevus in other Oxford dictionaries Definition of naevus in the US English dictionary