Definition
The forward edge of an airfoil — the part of a wing, propeller blade, or tail surface that meets the oncoming air first as the aircraft moves forward.
Plain English
The front edge of the wing — the rounded edge that hits the air first when the airplane moves forward.
Context Anchor
Seen when learning the parts of the wing and tail, during preflight inspection, and when discussing ice, damage, or airflow over the airplane.
Derivation
Leading' here means 'going first' or 'in front.' The leading edge is simply the edge that leads — the one out in front as the wing moves through the air. The opposite is the trailing edge, the edge that trails behind.
Why Pilots Care
Determines where lift is first generated, where stalls typically begin, and where ice or de-icing equipment is most often found.
Intuition Check
Leading edge does not mean the most important or most advanced part here. It means the physical front edge of the wing or tail surface as it moves into the air.
Example Sentence 1
During the preflight, the pilot ran a hand along the leading edge of each wing, checking for dents or ice.
Example Sentence 2
The pilot inspected the leading edge for dents before the next flight.