chestnut

Chestnut is a contraction of the obsolete word chesten (meaning both the tree and its fruit) plus nut. Chesten descends from Middle English chesteine, from Old French chastaigne, from Latin castanea, ultimately from Ancient Greek κᾰστᾰ́νειᾰ, a variant of κᾰ́στᾰνᾰ, 'sweet chestnut.'

Beyond naming the tree and its fruit, the word picked up a figurative sense for a stale, overused joke or story — possibly tied to an 1816 play in which a character is mocked for endlessly repeating a tale about a chestnut tree. Its adjective use, describing a reddish-brown color, likely grew from using the noun attributively.

Chestnut is a doublet of castanet, both tracing back to the same Latin root, castanea.