Barrel of the ear

Barrel \Bar"rel\ (b[a^]r"r[e^]l), n.[OE. barel, F. baril, prob.
   fr. barre bar. Cf. {Barricade}.]
   1. A round vessel or cask, of greater length than breadth,
      and bulging in the middle, made of staves bound with
      hoops, and having flat ends or heads; as, a cracker
      barrel. Sometimes applied to a similar cylindrical
      container made of metal, usually called a {drum}.
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   2. The quantity which constitutes a full barrel. This varies
      for different articles and also in different places for
      the same article, being regulated by custom or by law. A
      barrel of wine is 311/2 gallons; a barrel of flour is 196
      pounds.
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   3. A solid drum, or a hollow cylinder or case; as, the barrel
      of a windlass; the barrel of a watch, within which the
      spring is coiled.
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   4. A metallic tube, as of a gun, from which a projectile is
      discharged. --Knight.
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   5. A jar. [Obs.] --1 Kings xvii. 12.
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   6. (Zool.) The hollow basal part of a feather.
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   {Barrel bulk} (Com.), a measure equal to five cubic feet,
      used in estimating capacity, as of a vessel for freight.
      

   {Barrel drain} (Arch.), a drain in the form of a cylindrical
      tube.

   {Barrel of a boiler}, the cylindrical part of a boiler,
      containing the flues.

   {Barrel of the ear} (Anat.), the tympanum, or tympanic
      cavity.

   {Barrel organ}, an instrument for producing music by the
      action of a revolving cylinder.

   {Barrel vault}. See under {Vault}.
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