The Collaborative International Dictionary of English v.0.48:

miscegenate \miscegenate\ v.
   to marry or cohabit with a person of another race.
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

miscegenate
    v 1: marry or cohabit with a person of another race

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "miscegenate":
   be made one, be spliced, become one, contract matrimony, couple,
   cross, crossbreed, espouse, get hitched, hybridize, interbreed,
   intermarry, interwed, marry, mate, mongrelize, pair off, remarry,
   rewed, take to wife, wed, wive