Mixed blood
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
A person is "of mixed blood" who is descended from ancestors of different races or nationalities ; but particularly, in the United States, the term denotes a person one of whose parents (or more remote ancestors) was a negro.
See Hopkins v. Bowers, 111 N. C. 175, 16 S. E. 1.