# valve

Pronunciation: US say "VALV" /ˈvælv/; UK

## Noun

1. A device that controls the flow of a gas or liquid through a pipe, manifold, or other enclosed passage.
   - Simple: A device that controls how gas or liquid flows through a pipe or other space.
   - _The plumber shut off the main valve before replacing the cracked pipe._
   - _Pressure-relief valves on the boiler opened automatically as the steam built up._
2. A membranous flap, fold or partition, or a set of them, that lets the contents of a vessel or cavity pass one way while stopping or controlling flow the other way.
   - Simple: A thin flap inside a tube or space in the body that lets things flow one way but not back.
   - _The surgeon replaced the patient's damaged aortic valve with an artificial one._
   - _Leaky valves in the leg veins let blood pool and swell the veins._
3. In an internal combustion engine, a device that admits fuel and air into a cylinder or lets the burned gases escape.
   - Simple: A part in an engine, such as a car engine, that lets fuel and air in or burned gases out.
   - _Each cylinder in the engine has two intake valves and two exhaust valves._
   - _A burned exhaust valve can rob an engine of much of its power._
4. An electronic vacuum tube, a sealed tube with the air removed. *(British)*
   - Simple: A closed tube with no air inside that is used in electronic equipment.
   - _Guitarists still favor valve amps for their warm tone._
   - _He spent the weekend hunting for a replacement valve for his 1950s television set._
6. One of the separate pieces that make up a bivalve or multivalve shell.
   - Simple: One of the parts of a shell that is made of two or more pieces.
   - _Only the left valve of the fossil scallop was preserved in the rock._
   - _A chiton's shell is made of overlapping valves that let it curl into a ball._
7. One of the separate panels that make up a folding door or a window sash.
   - Simple: One of the panels of a folding door or of a window frame.
   - _Each valve of the folding door was carved with climbing vines._
   - _The carpenter rehung the window's valves so that they met neatly in the middle._
8. One of the pieces into which certain fruits naturally separate when they split open to release their seeds.
   - Simple: One of the parts that some seed pods split into when they open by themselves.
   - _As the capsule ripens, its valves pull apart and the seeds spill onto the ground._
   - _Each valve of the dried bean pod twisted sharply, flinging the seeds across the path._
9. Either of the two similar halves that together make up the shell of a diatom.
   - Simple: One of the two nearly matching halves of the shell of a diatom, a tiny living thing found in water.
   - _The pattern of pores on each valve helps scientists identify the diatom species._
   - _When a diatom divides, each daughter cell keeps one of the parent's valves and builds a new one._
10. A small part of the anther in certain plants, such as the barberry, that opens like a trapdoor to let the pollen escape.
   - Simple: A tiny flap on the pollen part of some flowers that opens like a little door to let the pollen out.
   - _In the barberry flower, each anther sheds its pollen through a little valve that lifts upward._
   - _Under the lens, the anther valves had curled back, each holding a sticky load of pollen._

## Verb

5. To control or regulate a flow by means of a valve.
   - Simple: To use a valve to control how much of something flows.
   - _Engineers valve the coolant through the system to hold the reactor at a steady temperature._
   - _The technician valved the steam into the turbine in short bursts._

## Origin

From Middle English valve, from Latin valva ("double door, valve"); it is a doublet of valva.

Source: DictionaryAI, https://dictionaryai.com/define/valve (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).