valve
/valv
/noun
1A device for controlling the passage of fluid or air through a pipe, duct, etc., especially an automatic device allowing movement in one direction only: a valve shuts off the flow from the boiler when the water is hot enough...
- The system is regulated by a height control valve which allows fluid to move between spheres to keep the car level.
- Its speed can be influenced by the waste-gate valve, which is controlled by the pressure-driven converter.
- Multifunctional tools, such as graders, require an electrical outlet and switches on the loader to control hydraulic diverter valves.
1.1British short for thermionic valve.You could even build a functional, if somewhat cumbersome, guitar amplifier with a hydraulic system replacing transistors or valves....
- Equipped with transistors instead of valves, it could be operated for 80 hours on four hearing aid batteries, costing 2s 6d each.
- Silicon chips transformed the then slowly evolving world of electrical circuits and valves to the vibrant and fast developing world of electronics.
1.2 Music A cylindrical mechanism in a brass instrument which, when depressed or turned, admits air into different sections of tubing and so extends the range of available notes.The later introduction of valves extended the versatility of brass instruments to cover the full chromatic scale....
- For trumpeters the left hand acts merely as a clamp holding the instrument whilst the three valves are operated by fingers of the right hand.
- The soloists played on natural horns, instruments that have no valves and are not as powerful as their modern descendants.
1.3 Anatomy & Zoology A membranous fold in a hollow organ or tubular structure, such as a blood vessel or the digestive tract, which maintains the flow of the contents in one direction by closing in response to any pressure from reverse flow: the aortic valve...
- When crocodiles are completely submerged, the ears and nostrils are closed by valves, and the eyes covered by membranes.
- During pregnancy, hormones relax the muscles in your digestive tract, including the valve in the esophagus.
- If the heart valves can't open and close correctly, blood can't flow smoothly.
2 Zoology Each of the halves of the hinged shell of a bivalve mollusc or brachiopod, or of the parts of the compound shell of a barnacle.The brachiopods from the limestone unit are mostly preserved as shells, most with valves conjoined....
- The two shell valves would have been rigidly fixed in place, and the dorsal margin could not have been more than a poorly elastic structure, if that.
- Note that each shell valve is symmetrical about the midline, but the two shell valves are often unequal in size.
2.1 Botany Each of the halves or sections into which a dry fruit (especially a pod or capsule) dehisces.Fruits were harvested just prior to dehiscence of the capsule valves....
- Dehiscence of the anther valves begins at the distal end.
- The fruit is a small oblong capsule with two valves containing many small seeds.
Derivatives
valved
[in combination]: a branchiopod has a two-valved outer covering
valveless
- It is equipped with a patented four-stroke valveless engine and automatic transmission.
- Being a valveless instrument, the Alphorn produces only those pitches that occur in the natural overtone or harmonic series.
- The low cardiac output manifests as fatigue, while the higher end diastolic pressure is transmitted backwards through the valveless pulmonary veins to the pulmonary capillaries, resulting in exertional dyspnoea.
valvule
Origin
Late Middle English (denoting a leaf of a folding or double door): from Latin valva.
Latin valva meant a leaf of a door and valve entered the language with this sense. Towards the end of the 18th century it was used to describe a door or flap controlling the flow of water and modern senses developed from this.