Nevus

nevus \ˈnē-vəs\ (plural nevi \ˈnē-ˌvī\) noun: a congenital or acquired usually highly colored area on the skin that is either flat or raised

Etymology: New Latin, from Latin naevus

Different kinds of nevi have different anatomical or physiological origins. Moles, for instance, are made up of melanocytes (the cells that produce the pigment melanin), while port-wine stains get their color from dilated capillaries.