Synonyms for Interbreeding (same or very similar meaning)
WordNet sense 1 ((genetics) the act of mixing different species or varieties of animals or plants and thus to produce hybrids):
cross, crossing, hybridization, crossbreeding, hybridisation, hybridizingWordNet sense 2 (reproduction by parents of different races (especially by white and non-white persons)):
miscegenationFrom the ODE community, based on WordNetadd/edit