valve

noun

ˈvalv 

1

a

: any of numerous mechanical devices by which the flow of liquid, gas, or loose material in bulk may be started, stopped, or regulated by a movable part that opens, shuts, or partially obstructs one or more ports or passageways

also : the movable part of such a device

b

: a device in a brass instrument for quickly channeling air flow through an added length of tube in order to change the fundamental tone by some definite interval

c

chiefly British : electron tube

2

[borrowed from Medieval Latin valva, going back to Latin] : a bodily structure (such as the mitral valve) that closes temporarily a passage or orifice or permits movement of fluid in one direction only

3

[borrowed from New Latin valva, going back to Latin] : one of the distinct usually hinged and movable pieces of which the shell of some shell-bearing animals (such as lamellibranch mollusks, brachiopods, and barnacles) consists

4

[borrowed from New Latin valva, going back to Latin]

a

: one of the segments or pieces into which a dehiscing capsule or legume separates

b

: the portion of various anthers (as of the barberry) resembling a lid

c

: one of the two encasing membranes of a diatom

5

archaic : a leaf of a folding or double door

valved

ˈvalvd 

adjective

valveless

ˈvalv-ləs 

adjective

Synonyms

• cock
• faucet
• gate
• spigot
• stopcock
• tap

Examples of valve in a Sentence

They turned off the main water valve to the house.

Recent Examples on the Web

Test to make sure the thermocouple and gas valve are operating properly by extinguishing the pilot light flame and checking to ensure the flow of gas is stopped. —Timothy Dale, Better Homes & Gardens, 19 Jan. 2025

The May 6 attempt was scrubbed two hours before liftoff because of valve on ULA’s upper Centaur stage that teams continue to investigate. —Richard Tribou, Orlando Sentinel, 15 Jan. 2025

The double-walled construction of the galleries provided significant protection, and at 10:45 a.m., the dampers — small valves that regulate airflow in a building’s HVAC system — were turned off, as was the air conditioning. —Jessica Gelt, Los Angeles Times, 9 Jan. 2025

But by then, a battery backup had failed, and the IT system that alerts staff to problems and controls the valves crashed. —Sabrina Moreno, Axios, 9 Jan. 2025

Word History

Etymology

Middle English, "leaf of a folding door," borrowed from Latin valva (usually in plural valvae) "double or folding door, leaf of such a door," perhaps going back to an early derivative of the base of volvere "to roll, make turn" — more at wallow entry 1

First Known Use

14th century, in the meaning defined at sense 5

Phrases Containing valve

• ball valve
• bicuspid valve
• brake/valve job
• butterfly valve
• check valve
• escape valve
• mitral valve
• safety valve
• semilunar valve
• slide valve
• tricuspid valve

Kids Definition

valve

noun

ˈvalv 

1

: a bodily structure (as in a vein or the heart) that closes temporarily to prevent passage of material or that allows movement of a fluid in one direction only

2

a

: a mechanical device by which the flow of liquid, gas, or loose material in bulk may be controlled by a movable part

also : the movable part of such a device

b

: a device in a brass musical instrument for quickly changing the tube length in order to make the tone higher or lower

3

: one of the separate pieces that make up the shell of some animals (as clams) and are often hinged

4

: one of the pieces into which a ripe seed capsule or pod separates

valved

ˈvalvd 

adjective

Medical Definition

valve

noun

ˈvalv 

1

: a bodily structure (as the mitral valve) that closes temporarily a passage or orifice or permits movement of fluid in one direction only

2

: any of various mechanical devices by which the flow of liquid (as blood) may be started, stopped, or regulated by a movable part that opens, shuts, or partially obstructs one or more ports or passageways

also : the movable part of such a device