I believe that the term is/was traditionally applied to persons of one-eighth or less black African ancestry.

Other terms for black-white racial composition - of French Creole origin, IIRC - are mulatto (half), quadroon (one fourth) and octaroon (one eighth).

At the height of the old white-supremacy regime in South Africa, I seem to remember that there were some thirty-two (32) racial groupings of people based on their ancestry.

Life should be led like a cavalry charge - Theodore Roosevelt