The Collaborative International Dictionary of English v.0.48:

Pipe \Pipe\, n. [AS. p[imac]pe, probably fr. L. pipare, pipire,
   to chirp; of imitative origin. Cf. Peep, Pibroch,
   Fife.]
   1. A wind instrument of music, consisting of a tube or tubes
      of straw, reed, wood, or metal; any tube which produces
      musical sounds; as, a shepherd's pipe; the pipe of an
      organ. "Tunable as sylvan pipe." --Milton.
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            Now had he rather hear the tabor and the pipe.
                                                  --Shak.
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   2. Any long tube or hollow body of wood, metal, earthenware,
      or the like: especially, one used as a conductor of water,
      steam, gas, etc.
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   3. A small bowl with a hollow stem, -- used in smoking
      tobacco, and, sometimes, other substances.
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   4. A passageway for the air in speaking and breathing; the
      windpipe, or one of its divisions.
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   5. The key or sound of the voice. [R.] --Shak.
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   6. The peeping whistle, call, or note of a bird.
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            The earliest pipe of half-awakened birds.
                                                  --Tennyson.
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   7. pl. The bagpipe; as, the pipes of Lucknow.
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   8. (Mining) An elongated body or vein of ore.
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   9. A roll formerly used in the English exchequer, otherwise
      called the Great Roll, on which were taken down the
      accounts of debts to the king; -- so called because put
      together like a pipe. --Mozley & W.
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   10. (Naut.) A boatswain's whistle, used to call the crew to
       their duties; also, the sound of it.
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   11. [Cf. F. pipe, fr. pipe a wind instrument, a tube, fr. L.
       pipare to chirp. See Etymol. above.] A cask usually
       containing two hogsheads, or 126 wine gallons; also, the
       quantity which it contains.
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   Pipe fitter, one who fits pipes together, or applies pipes,
      as to an engine or a building.

   Pipe fitting, a piece, as a coupling, an elbow, a valve,
      etc., used for connecting lengths of pipe or as accessory
      to a pipe.

   Pipe office, an ancient office in the Court of Exchequer,
      in which the clerk of the pipe made out leases of crown
      lands, accounts of cheriffs, etc. [Eng.]

   Pipe tree (Bot.), the lilac and the mock orange; -- so
      called because their were formerly used to make pipe
      stems; -- called also pipe privet.

   Pipe wrench, or Pipe tongs, a jawed tool for gripping a
      pipe, in turning or holding it.

   To smoke the pipe of peace, to smoke from the same pipe in
      token of amity or preparatory to making a treaty of peace,
      -- a custom of the American Indians.
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WordNet (r) 3.0 (2006):

pipe fitter
    n 1: a craftsman who installs and repairs pipes and fixtures and
         appliances [syn: plumber, pipe fitter]