noun
black chestnut (horse coat color)
A specific equine coat color term; used in horse breeding, racing, and veterinary contexts.
あの馬は黒栗毛の美しい毛並みをしている。
That horse has a beautiful black chestnut coat.
青毛 is a black coat, whereas 黒栗毛 is a dark chestnut, not a true black.
Compound of 黒 (black) and 栗毛 (chestnut coat color). The term describes a dark chestnut horse coat.