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.

Cultural norms prescribing that people marry inside their own social group or category.

the restriction of mating within determined social groups.

marriage within one's own tribe or group as required by custom or law

The custom of marrying only within the limits of a local community, clan or tribe (The New Shorter Oxford English Dictionary 1993, Volume 1, A-M p817)

inmarriage, marriage to an individual within a defined social group, category, or range.

a rule requiring marriage within a specified social or kinship group.

The practice of marrying within a social group. Endogamous societies have a high number of first and second cousin marriages.

This refers to marrying within the race.

Marriage to a person within one's own group (kin, caste, community).

Rules (not necessarily codified) requiring marriage within a group, e.g. religion, class, ethnicity. Endogamy strengthens ties within a group. (See exogamy)

Endogamy is the practice of marrying within a social group. Cultures who practice endogamy require marriage between specified social groups, classes, or ethnicities. A Danish endogamist would require marriage only to other Danes.