1Interbreeding and cultural intermixing of Spanish and American Indian people (originally in Mexico, and subsequently also in other parts of Latin America); miscegenation, racial and cultural intermixing.
2rare With the. The action or process of such racial and cultural intermixing.
3rare Latin American people of mixed American Spanish (especially Mexican) and American Indian parentage, considered collectively.
1940s; earliest use found in Hispanic American Historical Review. From Spanish mestizaje miscegenation, people of mixed race from mestizar to interbreed (from mestizo) + -aje.