Definition
Fixed or automatically opening gaps built into the leading edge of a wing that allow high-pressure air from beneath the wing to flow through to the upper surface at high angles of attack. This re-energizes the airflow over the top of the wing, delaying flow separation and allowing the wing to keep producing lift at slower speeds and steeper angles than it otherwise could.
Plain English
Slots are small openings near the front edge of the wing that let air pass from below to above. This keeps the air flowing smoothly over the top of the wing when flying slowly or at steep angles, which delays the stall.
Context Anchor
Seen in discussions of high-speed aircraft wing design and flight controls, especially where the airplane must still handle safely at slower speeds for takeoff, landing, or approach.
Derivation
A 'slot' is simply a narrow opening or gap. The 'leading edge' is the front of the wing, the part that meets the oncoming air first. So a leading edge slot is literally a narrow opening at the front of the wing.
Why Pilots Care
They lower stall speed and improve handling near the stall without adding drag or mechanical complexity at cruise speeds.
Grounding Statement
Picture air being fed through a narrow gap at the front of the wing to help smooth the airflow over the top surface.
Intuition Check
Do not think of leading edge slots as storage slots or simple cutouts. In aviation, they are shaped openings that manage airflow over the wing.
Example Sentence 1
The aircraft's fixed leading edge slots allowed it to maintain controlled flight at angles of attack that would have stalled a conventional wing.
Example Sentence 2
High-performance trainers use leading edge slots to allow steeper turns without the wing stalling prematurely.