vent \vent\ ve^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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see also:
fissure to give vent to to take vent vent feather vent field vent piece 
bush