Barrel

1. A tube through which a bullet travels when a gun is fired. The barrel of a rifle has spiral grooves.
2. A cylindrical container that holds liquids. The wine was stored in a barrel.
3. Informal. A large quantity. We had a barrel of fun at the party.
4. The quantity that a barrel (of any size) will hold. The well produced thousands of barrels of oil.
5. Any of various units of capacity; "a barrel of beer is 31 gallons and a barrel of oil is 42 gallons." Oil is measured by the barrel.