Definition
The aerodynamic and handling consequences that occur when an airplane is forced or allowed to leave the runway before it has reached an airspeed sufficient to sustain normal flight. Because the wing is operating at a high angle of attack with little excess airspeed, the airplane tends to settle back toward the runway, mush along in ground effect, suffer a marked loss of climb performance, and in some cases stall or strike the runway with the tail or main gear.
Plain English
What happens when the airplane is pulled off the ground too soon: it doesn't have enough speed to really fly, so it tends to sink, struggle to climb, and may even stall back onto the runway.
Context Anchor
Encountered during takeoff and lift-off training, especially when the pilot pulls back too strongly or tries to force the airplane off the runway before it has enough speed.
Derivation
Premature comes from the Latin praematurus, meaning 'too early' or 'before its time.' Lift-off is the moment the wheels leave the runway. Together the phrase literally means leaving the ground before the airplane is ready to fly.
Why Pilots Care
It sharply reduces climb capability and can lead to loss of control, runway contact, or collision with nearby obstacles.
Grounding Statement
Picture the airplane floating a few feet above the runway with the nose high, the controls feeling soft, and the airspeed not building enough for a safe climb.
Intuition Check
Do not assume that wheels off the runway means the takeoff is safely complete. Premature lift-off means the airplane left the ground before it had enough speed to climb safely.
Example Sentence 1
The instructor warned that a premature lift-off in a heavily loaded airplane could result in the tail striking the runway as the nose was raised too aggressively.
Example Sentence 2
Recognizing the effect of premature lift-off helps the pilot delay rotation until the proper speed is reached.