Definition 1 of 2
Plain English Meaning
Just before the wheels touch the runway, the pilot gently eases the nose up. This slows the airplane and softens the descent so it settles onto the runway instead of slamming into it.
Full Definition
The flare is the final phase of a normal landing in which the pilot smoothly raises the airplane's nose to progressively reduce the rate of descent and slow the airplane so it touches down on the main wheels at minimum safe airspeed, in a slightly nose-high attitude.
Context Anchor
You encounter this during the last few feet of a normal landing, after the approach and just before the wheels touch the runway.
Derivation
From the everyday word 'flare,' meaning to spread or curve outward. The 's 'flares ' from a descending line into one nearly parallel to the runway, hence the name.