cousin

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

• noun A child of one's aunt or uncle.
• noun A relative descended from a common ancestor, such as a grandparent, by two or more steps in a diverging line.
• noun A relative by blood or marriage; a kinsman or kinswoman.
• noun A member of a kindred group or country.
• noun Something similar in quality or character.
• noun Used as a form of address by a sovereign in addressing another sovereign or a high-ranking member of the nobility.

from The Century Dictionary.

• noun In general, one collaterally related by blood more remotely than a brother or sister; a relative; a kinsman or kinswoman; hence, a term of address used by a king to a nobleman, particularly to one who is a member of the council, or to a fellow-sovereign.
• noun Specifically, in modern usage The son or daughter of an uncle or an aunt, or one related by descent in a diverging line from a known common ancestor. The children of brothers and sisters are called cousins, cousins german, first cousins, or full cousins; children of first cousins are called second cousins, etc. Often, however, the term second cousin is loosely applied to the son or daughter of a cousin german, more properly called a first cousin once removed.
• Allied; kindred.
• An obsolete spelling of cozen.
• To call “cousin”; claim kindred with. See cousin, n.

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

• noun obsolete Allied; akin.
• noun One collaterally related more remotely than a brother or sister; especially, the son or daughter of an uncle or aunt.
• noun A title formerly given by a king to a nobleman, particularly to those of the council. In English writs, etc., issued by the crown, it signifies any earl.

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

• noun The son or daughter of a person’s uncle or aunt; a first cousin.
• noun Any relation who is not a direct ancestor or descendant; one more distantly related than an uncle, aunt, granduncle, grandaunt, nephew, niece, grandnephew, grandniece, etc.

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

• noun the child of your aunt or uncle