brunette
A girl or woman with brown or dark brown hair.
Brunette describes someone, usually a woman or girl, with brown or dark brown hair. While you might say a boy or man has brown hair, brunette is traditionally used for females.
Hair color words like brunette, blonde, and redhead help us describe people's appearance. Someone might say “the brunette girl in the blue jacket” to help identify which person they're talking about in a crowd.
The masculine form is brunet (without the final “e”), used for males with brown hair, though it's less common in everyday English.