- A device that admits fuel and air into the cylinder of an internal combustion engine, or one that allows combustion gases to exit.
- (botany) One of the pieces into which certain fruits naturally separate when they dehisce.
- (biology) One of the two similar portions of the shell of a diatom.
- A device that controls the flow of a gas or fluid through a pipe.
- (Britain) A vacuum tube.
- (biology) One of the pieces or divisions of bivalve or multivalve shells.
- (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 retard the flow in the opposite direction; as, the ileocolic, mitral, and semilunar valves.
- (botany) A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, as in the barberry.
- (transitive) To control (flow) by means of a valve.