aunt

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

• noun The sister of one's father or mother.
• noun The wife of a sibling of one's mother or father.
• noun Used as a form of address for an older woman, especially by children.

from The Century Dictionary.

• noun The sister of one's father or mother; also, in address or familiar use, the wife of one's uncle.
• noun Formerly used by alumni of Oxford and Cambridge as a title for the “sister university.”
• noun An old woman; an old gossip.
• noun A procuress; a loose woman.
• noun The head so used.

from the GNU version of the Collaborative International Dictionary of English.

• noun The sister of one's father or mother; -- correlative to nephew or niece. Also applied to an uncle's wife.
• noun obsolete An old woman; and old gossip.
• noun obsolete A bawd, or a prostitute.
• noun a puppet head placed on a pole and having a pipe in its mouth; also a game, which consists in trying to hit the pipe by throwing short bludgeons at it.

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

• noun A sister or sister-in-law of someone’s parent.
• noun A person's grandparent's sister or sister-in-law.
• noun A grandmother.
• noun An affectionate term for a woman of an older generation than oneself, especially a friend of one's parents, by means of fictive kin.

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

• noun the sister of your father or mother; the wife of your uncle