Barrel

n. [O. Fr. bareil, barriel, now baril, Pr. barril, barrial, It. barile, Sp. & Pg. barril, W. baril, Gael. baraille, from barra, bar, q. v. Cf. Fr. barrique, cask; Sp. barrica. See BARRICADE.]

1. A round vessel or cask, of more length than breadth, and bulging in the middle, made of staves and headings, and bound with hoops.
2. The quantity which such a vessel contains. Of wine measure, the English barrel contains 31½ gallons; of beer measure, 36 gallons; of ale, 32 gallons; and of beer-vinegar, 34 gallons.
3. Any hollow cylinder; a tube; as, the barrel of a gun; the barrel of a watch, within which the spring is coiled, and round which is wound the chain.

Barrel of a boiler, the cylindrical part of a boiler containing the flues. [See Illust. of Boiler.]—Barrel of the ear (Anat.), a cavity of the ear, situated within the membrane of the tympanum, by which it is separated from the external passage, or meatus;—more usually called the cavity of the tympanum.