The Collaborative International Dictionary of English v.0.48:

Blowgun \Blow"gun`\, n.
   A tube, as of cane or reed, sometimes twelve feet long,
   through which an arrow (sometimes poisoned) or other
   projectile may be impelled by the force of the breath. It is
   a weapon much used by certain Indians of America and the West
   Indies; -- called also blowpipe, and blowtube. See
   Sumpitan.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Blowtube \Blow"tube`\, n.
   1. A blowgun. --Tylor.
      [1913 Webster]

   2. A similar instrument, commonly of tin, used by boys for
      discharging paper wads and other light missiles.
      [1913 Webster]

   3. (Glassmaking) A long wrought iron tube, on the end of
      which the workman gathers a quantity of "metal" (melted
      glass), and through which he blows to expand or shape it;
      -- called also blowing tube, and blowpipe.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Blowpipe \Blow"pipe`\, n.
   1. A tube for directing a jet of air into a fire or into the
      flame of a lamp or candle, so as to concentrate the heat
      on some object.
      [1913 Webster]

   Note: It is called a mouth blowpipe when used with the mouth;
         but for both chemical and industrial purposes, it is
         often worked by a bellows or other contrivance. The
         common mouth blowpipe is a tapering tube with a very
         small orifice at the end to be inserted in the flame.
         The oxyhydrogen blowpipe, invented by Dr. Hare in
         1801, is an instrument in which oxygen and hydrogen,
         taken from separate reservoirs, in the proportions of
         two volumes of hydrogen to one of oxygen, are burned in
         a jet, under pressure. It gives a heat that will
         consume the diamond, fuse platinum, and dissipate in
         vapor, or in gaseous forms, most known substances.
         [1913 Webster]

   2. A blowgun; a blowtube.
      [1913 Webster]

   Blowpipe analysis (Chem.), analysis by means of the
      blowpipe.

   Blowpipe reaction (Chem.), the characteristic behavior of a
      substance subjected to a test by means of the blowpipe.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blowpipe
    n 1: a tube that directs air or gas into a flame to concentrate
         heat [syn: blowtube, blow tube, blowpipe]
    2: a tube through which darts can be shot by blowing [syn:
       blowgun, blowpipe, blowtube, blow tube]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "blowpipe":
   acetylene welder, automatic, bellows, blast lamp, blower, blowgun,
   blowtorch, blowtube, burner, firearm, flamethrower, gat, gun,
   handgun, heater, musket, peashooter, piece, pistol, repeater,
   revolver, rifle, rod, sawed-off shotgun, shooting iron, shotgun,
   six-gun, six-shooter, torch, welder, welding blowpipe