Plain English Meaning

The wings are angled backward from where they meet the body of the aircraft, rather than sticking straight out to the sides. This shape helps the airplane handle high speeds better and naturally tends to keep it pointed in the right direction.

Full Definition

A wing design feature in which the wings angle rearward from the fuselage rather than extending straight out perpendicular to it. Sweepback delays the onset of compressibility effects at high speeds and contributes to directional stability by causing the rearward wing to produce more lift than the forward wing during a yaw, which helps return the aircraft to coordinated flight.