Definitions 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:   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:   used of hair; of a golden brown to reddish brown color

  Example: "A chestnut horse"

• name:  A surname (common: 1 in 20000 families; popularity rank in the U.S.: #2677)