The Collaborative International Dictionary of English v.0.48:

Vent \Vent\ (v[e^]nt), n. [OE. fent, fente, a slit, F. fente a
   slit, cleft, fissure, from fendre to split, L. findere; but
   probably confused with F. vent wind, L. ventus. See
   Fissure, and cf. Vent to snuff.]
   1. A small aperture; a hole or passage for air or any fluid
      to escape; as, the vent of a cask; the vent of a mold; a
      volcanic vent.
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            Look, how thy wounds do bleed at many vents. --Shak.
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            Long 't was doubtful, both so closely pent,
            Which first should issue from the narrow vent.
                                                  --Pope.
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   2. Specifically:
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      (a) (Zool.) The anal opening of certain invertebrates and
          fishes; also, the external cloacal opening of
          reptiles, birds, amphibians, and many fishes.
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      (b) (Gun.) The opening at the breech of a firearm, through
          which fire is communicated to the powder of the
          charge; touchhole.
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      (c) (Steam Boilers) Sectional area of the passage for
          gases divided by the length of the same passage in
          feet.
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   3. Fig.: Opportunity of escape or passage from confinement or
      privacy; outlet.
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   4. Emission; escape; passage to notice or expression;
      publication; utterance.
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            Without the vent of words.            --Milton.
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            Thou didst make tolerable vent of thy travel.
                                                  --Shak.
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   To give vent to, to suffer to escape; to let out; to pour
      forth; as, to give vent to anger.

   To take vent, to escape; to be made public. [R.]

   Vent feather (Zool.), one of the anal, or crissal, feathers
      of a bird.

   Vent field (Gun.), a flat raised surface around a vent.

   Vent piece. (Gun.)
      (a) A bush. See 4th Bush, n., 2.
      (b) A breech block.
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