- The definition of a valve is a device that opens or closes to let things through or to prevent passage.
The part of your heart that opens and closes to let blood enter or to prevent blood from entering is an example of a valve.
- Archaic either of the halves of a double door or any of the leaves of a folding door
- a gate regulating the flow of water in a sluice, channel, etc.
- Anat. a membranous fold or structure which permits body fluids to flow in one direction only, or opens and closes a tube, chamber, etc.
- any of the segments into which a pod or capsule separates when it bursts open
- a lidlike part in some anthers, through which pollen is discharged
- either of the boxlike halves forming the cell walls of a diatom
- a device, esp. a rectifier, that allows current to flow in only one direction
- Brit. electron tube
- any device in a pipe or tube that permits a flow in one direction only, or regulates the flow of whatever is in the pipe, by means of a flap, lid, plug, etc. acting to open or block passage
- the flap, lid, plug, etc.
- Music a device in certain brass instruments, as the trumpet, that opens (or closes) an auxiliary to the main tube, lengthening (or shortening) the air column and lowering (or raising) the pitch
- each separate part making up the shell of a mollusk, barnacle, etc.
- any of the parts forming the sheath of an ovipositor in certain insects
Origin: ME, a door leaf from Classical Latin valva, leaf of a folding door, akin to volvere, to roll: see walk; valvesenses , , from Modern Latin valva from Classical Latin
- valveless adjective
Used by arrangement with John Wiley & Sons, Inc.
- Anatomy A membranous structure in a hollow organ or passage, as in an artery or vein, that folds or closes to prevent the return flow of the body fluid passing through it.
- a. Any of various devices that regulate the flow of gases, liquids, or loose materials through piping or through apertures by opening, closing, or obstructing ports or passageways.b. The movable control element of such a device.c. Music A device in a brass wind instrument that permits change in pitch by a rapid varying of the air column in a tube.
- Biology a. One of the paired, hinged shells of certain mollusks and of brachiopods.b. One of the two silicified halves of the cell wall of a diatom.c. The entire, one-piece shell of a snail and certain other mollusks.
- Botany a. One of the sections into which the wall of a seedpod or other dehiscent fruit splits.b. A lidlike covering of an anther.
- Chiefly British An electron tube or a vacuum tube.
- Archaic Either half of a double or folding door.
- To provide with a valve.
- To control by means of a valve.
Origin: Middle English, leaf of a door, from Latin valva; see wel-2 in Indo-European roots.
- valveˈless adjective
top: closed check valve
bottom: open check valve
valve - Medical Definition
- A membranous structure in a hollow organ or passage, as in an artery or vein, that folds or closes to prevent the return flow of the body fluid passing through it.
- Any of various devices that regulate the flow of gases, liquids, or loose materials through piping or through apertures by opening, closing, or obstructing ports or passageways.
- The movable control element of such a device.
valve - Science Definition
- a. Any of various mechanical devices that control the flow of liquids, gases, or loose material through pipes or channels by blocking and uncovering openings.b. The movable part or element of such a device.
- Any of various structures that prevent the backward flow of a body fluid, such as blood or lymph. Valves in the heart, veins, and lymphatic vessels contain flaps (known as cusps) that close in response to pressure created by the backflow of fluid.
- One of the paired hinged shells of certain mollusks, such as clams and oysters.
- See electron tube.
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