Plain English Meaning

A control in the cockpit that turns the fuel supply to the engine on or off, and on many airplanes also picks which tank the fuel comes from.

Full Definition

A cockpit-operated valve that allows the pilot to stop the flow of fuel from the airplane's fuel tanks to the engine. In most light airplanes it is combined with the fuel selector, which lets the pilot choose which tank feeds the engine or shut the supply off entirely.

Context Anchor

You will see this term in emergency procedures, especially engine fire checklists and fuel system discussions.

Derivation

Valve comes from an old word for a folding door. That helps here because a valve acts like a door for fuel: open lets fuel pass, closed stops it.