Endogamy

[en'dɒgәmi]

(noun.) marriage within one's own tribe or group as required by custom or law.

Typed by Brian--From WordNet

(n.) Marriage only within the tribe; a custom restricting a man in his choice of a wife to the tribe to which he belongs; -- opposed to exogamy.

Typist: Vilma

n. the custom forbidding a man to marry any woman who is not of his kindred.—adj. Endog′amous.

Typist: Trevor