Plain English Meaning
A small upward-angled extension on the end of a wing that reduces the swirling air at the wingtip, which makes the aircraft more efficient and saves fuel.
Full Definition
A small, near-vertical aerodynamic surface attached to the tip of an aircraft wing, designed to reduce induced drag by weakening the wingtip vortex that forms when high-pressure air beneath the wing spills around the tip into the lower-pressure air above it.
Context Anchor
Seen during aircraft walkarounds, in aircraft performance discussions, and when identifying aircraft wing designs.
Derivation
From 'wing' plus the diminutive suffix '-let,' meaning 'small wing.' The name reflects what it is: a little wing standing on the end of the main wing.
Why Pilots Care
Reduces fuel burn and increases range or payload by lowering drag without adding significant weight.
Analogy
A winglet is a little like a fence at the edge of a wing. It helps keep the air from spilling around the tip as strongly, which reduces wasted energy.
Intuition Check
A winglet is not a separate little wing meant to fly the airplane by itself. It is a wingtip device that helps the main wing work more efficiently.
Example Sentence 1
The 737-800 with winglets burns less fuel on long legs than the same aircraft without them.
Example Sentence 2
After installing winglets, the aircraft showed a measurable reduction in fuel flow at altitude.