Definition
The moment during the takeoff roll when the airplane's wings produce enough lift to overcome its weight and the wheels leave the runway surface, transitioning the aircraft from ground operation to flight.
Plain English
The instant the airplane stops rolling on the ground and starts flying.
Context Anchor
Used during takeoff training and takeoff discussions, especially when describing the exact moment the airplane leaves the surface.
Derivation
A straightforward compound: the airplane is 'lifted off' the ground by the lift its wings generate. The hyphenated form is the standard FAA spelling when used as a noun.
Why Pilots Care
Lift-off is the point at which the pilot must confirm adequate airspeed and begin the climb; insufficient speed here can lead to settling back onto the runway or loss of control.
Intuition Check
Lift-off does not mean the entire takeoff. It means the specific moment the airplane leaves the ground.
Example Sentence 1
The instructor called out the airspeed, and at 55 knots the airplane reached lift-off.
Example Sentence 2
A headwind reduced the distance required to reach lift-off during the short-field takeoff.