valve

American  

[valv] / vælv /

noun

valves plural

1. any device for halting or controlling the flow of a liquid, gas, or other material through a passage, pipe, inlet, outlet, etc.

2. a hinged lid or other movable part that closes or modifies the passage in such a device.

3. Anatomy. a membranous fold or other structure that controls the flow of a fluid, as one that permits blood to flow in one direction only.

4. (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.

5. Zoology.

   1. one of the two or more separable pieces composing certain shells.

   2. either half of the silicified shell of a diatom.

6. Botany.

   1. one of the segments into which a capsule dehisces.

   2. a flap or lidlike part of certain anthers.

7. Electronics (chiefly British). vacuum tube.

8. Archaic. one of the leaves of a double or folding door.

---

verb (used with object)

valved, valving

1. to provide with a means of controlling the flow of liquid, gas, etc., by inserting a valve.

valve British  

/ vælv /

noun

1. any device that shuts off, starts, regulates, or controls the flow of a fluid

2. anatomy a flaplike structure in a hollow organ, such as the heart, that controls the one-way passage of fluid through that organ

3. Also called: tube.   vacuum tube.  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 See also diode triode tetrode pentode

4. zoology any of the separable pieces that make up the shell of a mollusc

5. music 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

6. botany

   1. any of the several parts that make up a dry dehiscent fruit, esp a capsule

   2. either of the two halves of a diatom cell wall

7. archaic a leaf of a double door or of a folding door

---

valve Scientific  

/ vălv /

1. 1. Any of various mechanical devices that control the flow of liquids, gases, or loose material through pipes or channels by blocking and uncovering openings.

   2. The movable part or element of such a device.

2. 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.

3. One of the paired hinged shells of certain mollusks, such as clams and oysters.

4. See electron tube

---

Other Word Forms

Derived Forms

• undervalve
  noun
• valveless
  adjective
• valvelike
  adjective

Inflected Forms

Nouns

• valves
  plural

Etymology

Origin of valve

1350–1400; Middle English < Latin valvae leaves of a door

Explanation

A valve is a device that controls the flow of a liquid or gas. Before you fix the broken sink in your bathroom, you should turn the valve that shuts off the water. The simplest type of valve has a hinged flap allowing liquid to flow one direction, but blocking it from going the other way. This is called a "check valve." Anatomical valves — systems in your body that allow a flow of fluid, like the aortic valve near your heart — are structured very much the same way. The shells of mollusks like oysters and clams are also called valves. The word's earliest meaning was "one half of a folding door."

Example Sentences

"The overall effect is that our original goal for the price of Steam Machine is no longer viable," Valve added.

From BBC • Jun. 23, 2026

But no one is having more trouble than Valve, a privately-owned game studio that also runs the most popular PC game store, Steam.

From Barron's • May 29, 2026

Valve had no weight to throw around and had to pay up, or not have anything to sell.

From Barron's • May 29, 2026

Valve has announced a price increase of more than 40% - or nearly £200 - for its two Steam Deck models, citing "rising memory and storage costs".

From BBC • May 28, 2026

Rip joined Flip Villa and they jumped on the high speed track that would whisk them to Valve Two on the other side of the platform.

From Rip Foster Rides the Gray Planet by Goodwin, Harold L. (Harold Leland)

Related Words

• faucet
• pipe
• spigot