The Collaborative International Dictionary of English v.0.48:

Siphon \Si"phon\, v. t. (Chem.)
   To convey, or draw off, by means of a siphon, as a liquid
   from one vessel to another at a lower level.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Siphon \Si"phon\, n. [F. siphon, L. sipho, -onis, fr. Gr. ??? a
   siphon, tube, pipe.]
   1. A device, consisting of a pipe or tube bent so as to form
      two branches or legs of unequal length, by which a liquid
      can be transferred to a lower level, as from one vessel to
      another, over an intermediate elevation, by the action of
      the pressure of the atmosphere in forcing the liquid up
      the shorter branch of the pipe immersed in it, while the
      continued excess of weight of the liquid in the longer
      branch (when once filled) causes a continuous flow. The
      flow takes place only when the discharging extremity of
      the pipe ia lower than the higher liquid surface, and when
      no part of the pipe is higher above the surface than the
      same liquid will rise by atmospheric pressure; that is,
      about 33 feet for water, and 30 inches for mercury, near
      the sea level.
      [1913 Webster]

   2. (Zool.)
      (a) One of the tubes or folds of the mantle border of a
          bivalve or gastropod mollusk by which water is
          conducted into the gill cavity. See Illust. under
          Mya, and Lamellibranchiata.
      (b) The anterior prolongation of the margin of any
          gastropod shell for the protection of the soft siphon.
      (c) The tubular organ through which water is ejected from
          the gill cavity of a cephaloid. It serves as a
          locomotive organ, by guiding and confining the jet of
          water. Called also siphuncle. See Illust. under
          Loligo, and Dibranchiata.
      (d) The siphuncle of a cephalopod shell.
      (e) The sucking proboscis of certain parasitic insects and
          crustaceans.
      (f) A sproutlike prolongation in front of the mouth of
          many gephyreans.
      (g) A tubular organ connected both with the esophagus and
          the intestine of certain sea urchins and annelids.
          [1913 Webster]

   3. A siphon bottle.
      [1913 Webster]

   Inverted siphon, a tube bent like a siphon, but having the
      branches turned upward; specifically (Hydraulic
      Engineering), a pipe for conducting water beneath a
      depressed place, as from one hill to another across an
      intervening valley, following the depression of the
      ground.

   Siphon barometer. See under Barometer.

   Siphon bottle, a bottle for holding aerated water, which is
      driven out through a bent tube in the neck by the gas
      within the bottle when a valve in the tube is opened; --
      called also gazogene, and siphoid.

   Siphon condenser, a condenser for a steam engine, in which
      the vacuum is maintained by the downward flow of water
      through a vertical pipe of great height.

   Siphon cup, a cup with a siphon attached for carrying off
      any liquid in it; specifically (Mach.), an oil cup in
      which oil is carried over the edge of a tube in a cotton
      wick, and so reaches the surface to be lubricated.

   Siphon gauge. See under Gauge.

   Siphon pump, a jet pump. See under Jet, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

siphon
    n 1: a tube running from the liquid in a vessel to a lower level
         outside the vessel so that atmospheric pressure forces the
         liquid through the tube [syn: siphon, syphon]
    2: a tubular organ in an aquatic animal (especially in mollusks)
       through which water can be taken in or expelled [syn:
       siphon, syphon]
    v 1: convey, draw off, or empty by or as if by a siphon [syn:
         siphon, syphon, siphon off]
    2: move a liquid from one container into another by means of a
       siphon or a siphoning action; "siphon gas into the tank"

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "siphon":
   adjutage, aspirator, bleed, broach, canalize, carry, catheter,
   channel, channelize, conduct, convey, corkscrew, crowbar, decant,
   draft, draft off, drain, drainpipe, draw, draw from, draw off,
   efflux tube, empty, exhaust, extractor, fire hose, flue pipe,
   flume, forceps, funnel, garden hose, gas pipe, hose, hosepipe, let,
   let blood, let out, milk, nipple, organ pipe, phlebotomize,
   pincers, pipe, pipeline, pipette, piping, pliers, press, pump,
   pump out, put through, put through channels, reed, reed pipe,
   separator, siamese, siamese connection, siphon off, snorkel,
   soil pipe, standpipe, steam pipe, stem, straw, suck, suck out, tap,
   traject, transmit, trench, tube, tubing, tubulation, tubule,
   tubulet, tubulure, tweezers, vacuum pump, venesect, waste pipe,
   water pipe, wringer