It has extremely racist connotations in U.S. usage.

Thank you for your question.

The word is miscegenation but you should be careful in using it. According to Wikipedia “The term “miscegenation” has been used to refer to interracial marriage and interracial sex, and more generally to the global process of racial admixture that has taken place since the Age of Discoveries, particularly through the European colonization of the Americas and the Atlantic slave trade. Historically the term has been used in the context of ethnocentric or racist attitudes and practices, such as the enactment of laws banning interracial marriage and sex, so-called anti-miscegenation laws. It is therefore a loaded word and is considered offensive by many.

Today, the word “miscegenation” is still used when referring to past ethnocentric and racist attitudes and practices concerning multiraciality. It is also still in use by some as a general term encompassing the different social and demographic aspects of “race-mixing”. However, because of its controversial history, other terms such as “interracial” or “interethnic” are more common in contemporary usage. In genetics, the term “admixture” is used for the interbreeding of people of different ethnicities or races. Sociologists also use the terms “outmarriage” or exogamy (the opposite of “inmarriage” or endogamy) for marriage and procreation within marriage with someome from outside of one’s social group. However, the boundary of a particular social group does not have to be “racial”, it can also be based on religion, culture, lineage or ethnicity.”

I would suggest interracial dating/relationships, admixture, outmarriage or exogamy depending on context. Miscegenation is too loaded especially as there used to miscegenation laws banning such relationships in many places.

I have attached sources for your reference.

Regards

It’s a term that is pretty well out of use these days but you’ll find it if you conduct historical or legal research.

http://en.wikipedia.org/wiki/Interracial_dating