chest·nut 
(chĕsnŭt′, -nət)
(chĕsnŭt′, -nət)n.
1.
a. Any of several deciduous trees of the genus Castanea native to northern temperate regions, having alternate simple toothed leaves, and nuts that are enclosed in a prickly husk.
b. The often edible nut of any of these trees.
c. The wood of any of these trees.
2. Any of several other plants, such as the horse chestnut.
3. A moderate to deep reddish brown.
4. A reddish-brown horse.
5. A small hard callus on the inner surface of a horse's foreleg.
6. An old, frequently repeated joke, story, or song.
adj.
Of a moderate to deep reddish brown.
[Earlier chesten (from Middle English chesteine, from Old French chastaigne, from Latin castanea, from Greek kastaneā, chestnut tree, from kastana, chestnuts; akin to Armenian kask, chestnut, both Greek and Armenian probably being of substrate origin) + NUT. Noun, sense 6, perhaps in reference to unpalatability of stale chestnuts, or to the play The Broken Sword (1816) by British playwright William Dimond (c.1784-1837?), in which one character begins to tell an anecdote involving a cork oak, and another interrupts him by exclaiming Chestnut! and says that in twenty-six previous tellings of the same anecdote, the tree had been a chestnut.]
chestnutAmerican chestnut
Castanea dentata