1900; see Amerind, of which it is the derived adjective.

"offspring of a person of mixed blood," especially a person of mixed Spanish and Amerindian parentage," 1580s, from Spanish mestizo, Portuguese mestiço, "of mixed European and Amerindian parentage," from Late Latin mixticius "mixed, mongrel," from Latin mixtus "mixed," past participle of miscere "to mix, mingle" (from PIE root *meik- "to mix"). Fem. form mestiza is attested from 1580s. Compare mustee.