In the colonial societies of the Americas and Australia, a quadroon or quarteron was a person with one-quarter African/Aboriginal and three-quarters European ancestry. Similar classifications were octoroon for one-eighth black and quintroon for one-sixteenth black.

In societies that regard some races or ethnic groups of people as dominant or superior and others as subordinate or inferior, hypodescent refers to the automatic assignment of children of a mixed union to the subordinate group. The opposite practice is hyperdescent, in which children are assigned to the race that is considered dominant or superior.