Plain English Meaning
A way of setting the altimeter so that it shows your height above the airport rather than your height above sea level. With QFE set, the altimeter reads zero on the runway.
Full Definition
QFE is an altimeter setting based on the actual atmospheric pressure at a specific airfield's elevation. When the altimeter is set to QFE, it reads zero feet when the aircraft is on the ground at that airfield, and it indicates height above that airfield's elevation while in flight. QFE is used in some countries (notably parts of Europe, Russia, and China) for departures, approaches, and landings, particularly below the transition altitude.
Context Anchor
Seen in instrument discussions and in countries or that use height above the airport instead of above sea level.