mulatto

Mulatto denotes a person with one white parent and one black parent or a person who has both black ancestry and white ancestry.  The term may be perceived as pejorative in some cultures and situations.  Its current usage varies greatly.

The etymology of the term is uncertain. It may be derived from the Portuguese and Spanish word mulato, which itself is derived from mula, mule; from Old Spanish; from Latin mūlus), by analogy with the mule, which is the hybrid offspring of a horse and a donkey…

Wikipedia