Definition of "Chestnut" :

noun: a dark golden-brown or reddish-brown horse

noun: a small horny callus on the inner surface of a horse's leg

noun: the brown color of chestnuts

noun: edible nut of any of various chestnut trees of the genus Castanea

noun: any of several attractive deciduous trees yellow-brown in autumn; yield a hard wood and edible nuts in a prickly bur

noun: wood of any of various chestnut trees of the genus Castanea

adjective: (of hair or feathers) of a golden brown to reddish brown color

"A chestnut horse."