Valve

Part of speech: noun

Pronunciation: /ˈvælv/

Definitions

1. A device that controls the flow of liquid, gas, or other material through a pipe or passage by opening, closing, or partially obstructing it
2. A mechanism that regulates the passage of fluids or gases within a system by either allowing, blocking, or restricting their flow
3. An apparatus that manages the movement of liquids or gases by adjusting openings in a pipeline, thus facilitating or hindering their passage

Etymology: The Latin "valva" meant a leaf of a double door, the hinged panel that swings open and shut, and it is from this door sense that English gets "valve". The idea carried over easily: a hinged plate that opens and closes an passage is a valve in both cases, whether the passage is a doorway or a pipe. The English word came through Middle English, and it has a close relative in the word "valva" itself, which survived in Latin-derived technical use, so the two forms are doublets. Over the centuries the meaning narrowed from any hinged leaf to the mechanical device that controls flow in engines, plumbing, and the human heart. The heart's valves, for example, are flaps that let blood move one way only, which is the same job a pipe valve does for water.

Synonyms: gate, stopcock, faucet, regulator, mechanism