siphonsi·phon also sy·phon (s??f?n)n.1. A tube that carries a liquid from a higher level up and over a barrier and then down to a lower level, with the flow maintained by gravity and atmospheric pressure as long as the tube remains filled. 2. Zoology A tubular organ, especially of aquatic invertebrates such as squids or clams, by which water is taken in or expelled.v. si·phoned, si·phon·ing, si·phons also sy·phoned or sy·phon·ing or sy·phons v.tr.1. To draw off or convey (a liquid) through a siphon.2. To take or transfer (something), often illicitly: siphon money from an account; siphon customers from a competitor.v.intr. To pass through a siphon.[Middle English, from Latin s?ph?, s?ph?n-, from Greek s?ph?n.]si?phon·al, si·phon?ic adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.siphon (?sa?f?n) or syphonn1. (General Physics) a tube placed with one end at a certain level in a vessel of liquid and the other end outside the vessel below this level, so that liquid pressure forces the liquid through the tube and out of the vessel by gravity2. (Brewing) See soda siphon3. (Zoology) zoology any of various tubular organs in different aquatic animals, such as molluscs and elasmobranch fishes, through which a fluid, esp water, passesvb (General Physics) (often foll by off) to pass or draw off through or as if through a siphon[C17: from Latin s?ph?, from Greek siph?n siphon] ?siphonage n ?siphonal, siphonic adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014si?phon or sy?phon (?sa? f?n) n., v. -phoned, -phon?ing. n. 1. a U-shaped pipe that uses atmospheric pressure to draw liquid from one container, place, or level to another. 2. a projecting tubular part of some animals, esp. certain mollusks, through which liquid enters or leaves the body. v.t., v.i. 3. to convey, draw, or pass through or as if through a siphon (sometimes fol. by off). [1650?60;