What is the meaning of Chestnut?

A tree or shrub of the genus Castanea.

A nut of this tree or shrub.

A dark, reddish-brown colour, as seen on the fruit of the chestnut tree.

A reddish-brown horse.

Wood of a chestnut tree.

An old joke; a worn-out meme, phrase, ploy, etc. so often repeated as to have grown tiresome or ineffective (often in the phrase "old chestnut").

A round or oval horny plate found on the inner side of the leg of a horse or other animal, similar to a birthmark on a human.

The horse-chestnut.

Of a deep reddish-brown colour, like that of a chestnut.

Source: wiktionary.org