The Collaborative International Dictionary of English v.0.48:

Miscegenation \Mis`ce*ge*na"tion\, n. [L. miscere to mix + the
   root of genus race.]
   A mixing of races; amalgamation, as by intermarriage of black
   and white.

   Note: Until the late twentieth century, misceganation was a
         crime in some states of the Southern United States.
         [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

miscegenation
    n 1: reproduction by parents of different races (especially by
         white and non-white persons) [syn: miscegenation,
         crossbreeding, interbreeding]

Moby Thesaurus II by Grady Ward, 1.0:

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