From Longman Dictionary of Contemporary Englishvalvevalve /vælv/ ●○○ noun [countable] 1 
TEMa part of a tube or pipe that opens and shuts like a door to control the flow of liquid, gas, air etc passing through it heart valves2 
APMthe part on a trumpet or similar musical instrument that you press to change the sound of the note3 British EnglishTEE a closed glass tube used to control the flow of electricity in old radios, televisions etc SYN vacuum tube American English
TEMa part of a tube or pipe that opens and shuts like a door to control the flow of liquid, gas, air etc passing through it heart valves2 APMthe part on a trumpet or similar musical instrument that you press to change the sound of the note3 British EnglishTEE a closed glass tube used to control the flow of electricity in old radios, televisions etc SYN vacuum tube American EnglishExamples from the Corpus
valve• Below this a valve closes, dividing the airflow to the engine so that it runs as two separate three cylinder units.• The engine depends heavily upon turbocharging and on five valves per cylinder for its 150 horsepower.• Sadly today, the making of valves is a dying art.• Secrecy sang in the static air, like an old valve radio with the volume turned down.• The solution, if that is the case, is to install a pressure-reducing valve on the water system.• The margins of the valves are often wavy, and deeply folded in other species.• His slide work caused many to accuse him of using an easier-to-use valve trombone.• This machine used valves rather than transistors or microchips and required input in the form of punched cards.Origin valve (1400-1500) Latin valva “part of a door” 