/vlv; vælv/
n
1 mechanical device for controlling the flow of air, liquid or gas in one direction only 阀; 阀门; 活门
*the inlet/outlet valves of a petrol or steam engine 汽油发动机或蒸汽机的进给[排放]阀
* the valve of a bicycle tyre 自行车胎的气嘴
* a safety, exhaust valve 安全阀、排气阀. =>illus at App
1 见附录1插图, page xiii. Cf 参看 tap1 1.
2 structure in the heart or in a blood-vessel allowing the blood to flow in one direction only （心脏或血管的）瓣膜.
3 device in certain brass musical instruments, eg cornets, for changing the pitch by changing the length of the column of air （管乐器的）活塞. =>illus at App
1 见附录1插图, page x.
4 (biology 生) each half of the hinged shell of oysters, mussels, etc 贝壳瓣. Cf 参看 bivalve.
5 = vacuum tube.

n[C]

[Date: 1400-1500; Language: Latin;Origin: valva 'part of a door']
a 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 valves
mouthpiece, valve
the part on a trumpet or similar musical instrument that you press to change the sound of the note
BrE a closed glass tube used to control the flow of electricity in old radios, televisions etc
American Equivalent: vacuum tube