noun
black hair; black fur
Refers to black hair or fur of animals, or sometimes human hair in descriptive contexts.
その犬は黒毛が美しい。
That dog has beautiful black fur.
彼女は黒毛をなびかせて歩いた。
She walked with her black hair flowing.
noun
black-haired horse
Specifically a horse with a black coat; used in equestrian or farming contexts.
あの黒毛は足が速い。
That black-haired horse is fast.