Definition
The outermost end of an airfoil — most commonly the wingtip — where the upper and lower surfaces of the wing come together and the wing terminates laterally. Because higher-pressure air beneath the wing spills around this end into the lower-pressure area above, the airfoil tip is the source of wingtip vortices and contributes to induced drag.
Plain English
The far end of the wing where it stops. Air leaks around this end from below to above, which creates a swirling flow and adds drag.
Context Anchor
Seen in discussions of wing shape, wingtip vortices, induced drag, and why a real wing behaves differently from a flat two-dimensional airfoil drawing.
Derivation
‘Airfoil’ is the wing’s shaped surface that produces lift; ‘tip’ is the far end of something. Together, the airfoil tip is simply where that lifting surface ends — and that boundary is where the pressure difference between top and bottom can finally escape sideways.
Why Pilots Care
Airfoil tips create wingtip vortices that increase drag and can affect nearby aircraft.
Intuition Check
Do not read “tip” as meaning only a sharp point. In this context, the airfoil tip is the whole outer end area of the wing or lifting surface.
Example Sentence 1
Pressure differences between the upper and lower surfaces equalize at the airfoil tip, producing the swirling vortex trailing behind the wing.
Example Sentence 2
Winglets were added to reduce the strength of the flow at each airfoil tip.