noun

• (countable) A round (cylindrical) vessel, such as a cask, of greater length than breadth, and bulging in the middle, made of staves bound with hoops, and having flat ends (heads). The word is sometimes applied to a similar cylindrical container made of metal, usually called a drum.
  "Near-synonym: cask"
• (countable) A round (cylindrical) vessel, such as a cask, of greater length than breadth, and bulging in the middle, made of staves bound with hoops, and having flat ends (heads). The word is sometimes applied to a similar cylindrical container made of metal, usually called a drum.
  "Barrels came in firkins, nine gallons; kilderkins, eighteen gallons; halves, twenty-seven gallons; barrels, thirty-six gallons and hogsheads, fifty-four."
• (automotive) A venturi (in carburetion).
• (television) A ceiling-mounted tube from which lights are suspended.
  "Moreover, it adds to difficulties in adjusting/servicing lamps located over high scenery, ceilings etc., where the barrel networks cannot be lowered or reached."

verb

• (transitive) To put or to pack in a barrel or barrels.
• (intransitive) To move quickly or in an uncontrolled manner.
  "He came barrelling around the corner and I almost hit him."
• (intransitive) To assume the shape of a barrel; specifically, of the image on a computer display, television, etc., to exhibit barrel distortion, where the sides bulge outwards.