A pigmented lesion of the skin. When raised, it is commonly referred to as a mole. A nevus (plural is nevi) may be light brown to almost black and may have hair growing from it. Nevi usually appear after 5 yrs of age, but can develop earlier. If a nevus is large, changes color, or grows you should report this to your doctor. Occasionally, moles may become malignant. Small moles are common; the average light skinned adult has 10-30 of them.