Plain English Meaning
A gauge in the cockpit that shows how close the wing is to stalling. It tells the pilot whether they have plenty of lift in reserve or whether they are getting near the point where the wing will stop flying.
Full Definition
A cockpit instrument that displays the wing's current angle of attack — the angle between the wing's chord line and the oncoming airflow — relative to the angle at which the wing will stall. It typically shows the pilot how much usable lift margin remains before the critical (stalling) angle of attack is reached, often using a color-coded scale, lighted segments, or a moving needle.