a large vessel or cask, of an oblong form, largest in the middle, and diminishing towards its two ends, girt about with hoops, and used for stowing several kinds of merchandise for convenience of carriage; as brandy, oil, sugar, skins, &c.

Tun is also the name of a measure. A tun of wine is four hogsheads; of timber, a square of forty solid feet; and of coals, twenty hundredweight.