Siphon  —n. 1 tube shaped like an inverted v or u with unequal legs, used to convey liquid from a container to a lower level by atmospheric pressure. 2 bottle from which aerated water is forced by the pressure of gas. —v. (often foll. By off) 1 (cause to) flow through a siphon. 2 divert or set aside (funds etc.). [greek, = pipe]