- 1(also chestnut tree) [countable] a large tree with spreading branches, that produces smooth brown nuts inside cases that are covered with spikes. There are several types of chestnut trees. see also horse chestnut
- 2[countable] a smooth brown nut of a chestnut tree, some types of which can be eaten roasted chestnuts The dessert was a rich mixture of chestnut purée and cream.
- 3 [uncountable] a deep reddish-brown color
- 4[countable] a horse of a reddish-brown color
- 5 old chestnut [countable] (informal) an old joke or story that has been told so many times that it is no longer amusing or interesting