valve

noun

1. A device that controls the flow of a gas or fluid through a space, such as a pipe, manifold, or plenum.

   “open the valve”

   “close the valve”

   “shut off the valve”

   “An oil refinery has an impressively vast number and variety of valves.”

2. A device that controls the flow of a gas or fluid through a space, such as a pipe, manifold, or plenum.

   “Near-synonym: poppet valve”

   “In nearly all internal combustion engines, the valves are of the poppet type.”

3. 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 ileocecal valve”

   “the atrioventricular valves”

4. One of the leaves of a folding door or of a window sash.
5. (British)A vacuum tube.
6. One of the pieces into which certain fruits naturally separate when they dehisce.
7. A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, such as in the barberry.
8. One of the pieces or divisions of bivalve or multivalve shells.
9. One of the two similar portions of the shell of a diatom.

verb

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