- any device for halting or controlling the flow of a liquid, gas, or other material through a passage, pipe, inlet, outlet, etc.
- a hinged lid or other movable part that closes or modifies the passage in such a device.
- a membranous fold or other structure that controls the flow of a fluid, as one that permits blood to flow in one direction only.
- (in musical wind instruments of the trumpet class) a device for changing the length of the air column to alter the pitch of a tone.
- Zoology.
- one of the two or more separable pieces composing certain shells.
- either half of the silicified shell of a diatom.
- Botany.
- one of the segments into which a capsule dehisces.
- a flap or lidlike part of certain anthers.
- vacuum tube (def. 1).
- one of the leaves of a double or folding door.
- to provide with a means of controlling the flow of liquid, gas, etc., by inserting a valve.
- any device that shuts off, starts, regulates, or controls the flow of a fluid
- a flaplike structure in a hollow organ, such as the heart, that controls the one-way passage of fluid through that organ
- an evacuated electron tube containing a cathode, anode, and, usually, one or more additional control electrodes. When a positive potential is applied to the anode, electrons emitted from the cathode are attracted to the anode, constituting a flow of current which can be controlled by a voltage applied to the grid to produce amplification, oscillation, etc
- any of the separable pieces that make up the shell of a mollusc
- a device on some brass instruments by which the effective length of the tube may be varied to enable a chromatic scale to be produced
- botany
- any of the several parts that make up a dry dehiscent fruit, esp a capsule
- either of the two halves of a diatom cell wall
- a leaf of a double door or of a folding door
