Miscegenation ( mih-SEJ-ə-NAY-shən) is sexual relations or marriage between people who are considered to be members of different races. The word, now usually considered pejorative, is derived from a combination of the Latin terms miscere ("to mix") and genus ("race"). The word first appeared in Miscegenation: The Theory of the Blending of the Races, Applied to the American White Man and Negro, a pretended anti-abolitionist pamphlet David Goodman Croly and others published anonymously in advance of the 1864 U.S. presidential election. The term came to be associated with laws that banned interracial marriage and sex, which were known as anti-miscegenation laws.

Although the term "miscegenation" was formed from the Latin miscere "to mix" plus genus "race" or "kind", and it could therefore be perceived as being value-neutral, it is almost always a pejorative term which is used by people who believe in racial superiority or purity. Less loaded terms for multiethnic relationships, such as interethnic or interracial marriages, and mixed-race, multiethnic, or multiracial people, are more common in contemporary usage.