liver spot

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A benign, localized brownish patch on the skin, often occurring in old age and usually in fair-skinned people with sun-damaged skin.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A dark brown blemish on the skin, usually caused by exposure to the sun.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a type of skin disease that causes brown spots on the skin