valve

Etymology

From Middle English valve, from Latin valva (“double door, valve”). Doublet of valva.

noun

1. A device that controls the flow of a gas or fluid through a pipe.
   shut off the valve
   open the valve
2. A device that admits fuel and air into the cylinder of an internal combustion engine, or one that allows combustion gases to exit.
3. (anatomy) One or more membranous partitions, flaps, or folds, which permit the passage of the contents of a vessel or cavity in one direction, but stop or control the flow in the opposite direction
   the ileocolic, mitral, and semilunar valves
4. One of the leaves of a folding-door, or a window-sash.
5. (Britain) A vacuum tube.
6. (botany) One of the pieces into which certain fruits naturally separate when they dehisce.
7. (botany) A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, such as in the barberry.
8. (biology) One of the pieces or divisions of bivalve or multivalve shells.
9. (biology) One of the two similar portions of the shell of a diatom.

verb

1. (transitive) To control (flow) by means of a valve.