[si.phon] n [F siphon, fr. L siphon-, sipho tube, pipe, siphon, fr. Gk siphon] (1659) 1 a: a tube bent to form two legs of unequal length by which a liquid can be transferred to a lower level over an intermediate elevation by the pressure of the atmosphere in forcing the liquid up the shorter branch of the tube immersed in it while the excess of weight of the liquid in the longer branch when once filled causes a continuous flow b usu syphon : a bottle for holding aerated water that is driven out through a bent tube in its neck by the pressure of the gas when a valve in the tube is opened
2: any of various tubular organs in animals and esp. mollusks or arthropods that are used for drawing in or ejecting fluids--see clam illustration
[2]siphon vb si.phoned ; si.phon.ing vt (1859): to convey, draw off, or empty by or as if by a siphon--often used with off ~ vi: to pass by or as if by a siphon