The Collaborative International Dictionary of English v.0.48:

Intermarriage \In`ter*mar"riage\, n.
   Connection by marriage; reciprocal marriage; giving and
   taking in marriage, as between two families, tribes, races,
   castes, or nations.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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,
         intermarriage] [ant: endogamy, inmarriage,
         intermarriage]
    2: marriage within one's own tribe or group as required by
       custom or law [syn: endogamy, intermarriage,
       inmarriage] [ant: exogamy, intermarriage]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "intermarriage":
   a world-without-end bargain, alliance, bed, bond of matrimony,
   bridebed, cohabitation, conjugal bond, conjugal knot, coverture,
   holy matrimony, holy wedlock, husbandhood, ill-assorted marriage,
   interracial marriage, marriage, marriage bed, marriage sacrament,
   match, matrimonial union, matrimony, mesalliance, misalliance,
   miscegenation, mixed marriage, nuptial bond,
   sacrament of matrimony, spousehood, union, wedded bliss,
   wedded state, weddedness, wedding knot, wedlock, wifehood