exogamy

from WordNet (r) 3.0 (2006)

exogamy
    n 1: marriage to a person belonging to a tribe or group other
         than your own as required by custom or law [syn: {exogamy},
         {intermarriage}] [ant: {endogamy}, {inmarriage},
         {intermarriage}]

from The Collaborative International Dictionary of English v.0.48

Exogamy \Ex*og"a*my\, n.
   The custom, or tribal law, which prohibits marriage between
   members of the same tribe; marriage outside of the tribe; --
   opposed to {endogamy}. --Lubbock.
   [1913 Webster]

[email protected]