Source : Webster's Revised Unabridged Dictionary (1913)

Intermarriage \In`ter*mar"riage\, n.
   Connection by marriage; reciprocal marriage; giving and
   taking in marriage, as between two families, tribes, castes,
   or nations.

Source : WordNet®

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