clan

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

• noun A traditional social unit in the Scottish Highlands, consisting of a number of families claiming a common ancestor and following the same hereditary chieftain.
• noun A division of a tribe tracing descent from a common ancestor.
• noun A large group of relatives, friends, or associates.

from The Century Dictionary.

• noun A social unit in a tribe in which descent is reckoned in the maternal line; a group of people supposed to be descended from a common ancestor, descent being reckoned in the female line. In this sense it is opposed to gens, the social unit in a tribe in which descent is reckoned in the paternal line.
• noun A race; a family; a tribe; an association of persons under a chieftain; especially, such a family or tribe among the Highlanders of Scotland.
• noun Figuratively, a clique, sect, set, society, or body of persons closely united by some common interest or pursuit, and supposed to have a spirit of exclusiveness toward others.
• noun Synonyms Tribe, Race, etc. See people.

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

• noun A tribe or collection of families, united under a chieftain, regarded as having the same common ancestor, and bearing the same surname.
• noun A clique; a sect, society, or body of persons; esp., a body of persons united by some common interest or pursuit; -- sometimes used contemptuously.

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

• noun anthropology A group of people all descended from a common ancestor, in fact or belief.
• noun A traditional social group of families in the Scottish Highlands having a common hereditary chieftain
• noun Any association of people behaving clannishly.
• noun video games A group of players who habitually play on the same team in multiplayer games.

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

• noun group of people related by blood or marriage