Final answer:
The angle of attack at which an airplane stalls is referred to as the critical angle of attack.
Step-by-step explanation:
In aviation, the angle of attack refers to the angle between the oncoming air or relative wind and the chord line of the wing. When an airplane stalls, it means that the airflow over the wing becomes disrupted, resulting in a loss of lift.
The angle of attack at which an airplane stalls is usually a specific value, unique to each aircraft, and is referred to as the critical angle of attack.