Definition of "chestnut" in English

noun

1. (countable) An edible nut (technically a fruit) of the Spanish chestnut or sweet chestnut tree (Castanea sativa); also (chiefly preceded by a descriptive word), a nut from a related shrub or tree; or a similar nut from an unrelated plant.

2. (countable) In full chestnut tree: the shrub or tree that bears this nut, the Spanish chestnut or sweet chestnut (Castanea sativa); also (chiefly preceded by a descriptive word), a shrub or tree of the genus Castanea.

3. (by extension) Things resembling a chestnut fruit in appearance or colour.

4. (countable, figurative) Chiefly in old chestnut: a joke, meme, phrase, ploy, etc. which has been repeated so often as to have grown ineffective or tiresome; a cliché.

adjective

1. Of a deep reddish-brown colour, like that of a chestnut fruit (noun, sense 1).

   • chestnut hair