chestnut(redirected from chestnut rule)
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chestnut/chest·nut/ (chest´nut) a tree of the genus Castanea or a nut of various species; the wood and leaves of C. dentata (American chestnut) contain tannin and it has been used as an astringent and in pertussis.
1. flattened, oval masses of horn on the medial surface of the forearm and the hock of the horse. Those on the forelimb are just proximal to the carpus, those on the hindlimb are at the distal end of the tarsus. In donkeys the hindlimb chestnut is very small, in mules it is absent. They are regarded as being vestiges of the carpal and tarsal pads.
2. fruit of the chestnut tree Castanea sativa.
3. a popular coat color in horses. A deep reddish brown varying from a red dominance or light chestnut, to a heavier brown tone, liver or deep chestnut. Mixed with white hairs is a chestnut roan.
mating two chestnut horses will not produce offspring with black, gray, brown or bay coat colors.
occurs in cattle when limb badly swollen or injured in grass fire.