Nevus (or naevus, plural nevi, from nævus, Latin for birthmark)'s the medical term for sharply-circumscribed and chronic lesions of the skin. These lesions are commonly named birthmarks and moles. By definition, nevi are benign. Using the term nevus and nevi loosely, most physicians and dermatologists are actually referring to a variant of nevus called the "melanocytic nevus", which are composed of melanocytes. Histologically, melanocytic nevi are differentiated from lentigines (also a typ… (More on Naevus)