Plain English Meaning
Keeping the airplane flying the way you want it to fly. Whatever else is happening, your first job is to keep the wings, nose, and speed where they need to be so the airplane stays under your command.
Full Definition
The pilot's continuous task of keeping the airplane flying within safe limits of attitude, airspeed, altitude, and flightpath, particularly when faced with an emergency, abnormal condition, or unexpected upset. It is the first priority in the established hierarchy of aviate, navigate, communicate.
Context Anchor
Seen in discussions of loss of control, emergency handling, upset recovery, stalls, spins, and any where the pilot’s first job is to keep the airplane under .