Source : Webster's Revised Unabridged Dictionary (1913)

Exogamous \Ex*og"a*mous\, a. [Exo- + Gr. ? marriage.]
   Relating to exogamy; marrying outside of the limits of one's
   own tribe; -- opposed to endogenous.

Source : WordNet®

exogamous
     adj 1: characterized by or fit for fertilization by a flower that
            is not closely related [syn: {exogamic}] [ant: {autogamous},
             {endogamous}]
     2: pertaining to or characterized by the custom of marrying
        only outside the limits of a clan or tribe [syn: {exogamic}]
        [ant: {endogamous}]