Plain English Meaning
The part of the flight where the pilot lines the airplane up with the runway and descends toward it, getting the aircraft into the right speed and configuration to land.
Full Definition
The phase of flight in which the airplane descends from the traffic pattern or final approach fix toward the runway, following a defined path that aligns the aircraft with the landing surface and stabilizes airspeed, configuration, and descent rate for touchdown.
Context Anchor
You will see this term in landing discussions, traffic pattern work, instrument flying, and any where the airplane is being set up to land.