critical angle noun3 •The angle of incidence beyond which light traveling through a medium experiences total internal reflection upon encountering a boundary with a less refractive medium. •The angle of attack beyond which an airfoil stalls, experiencing a decrease in lift and increase in drag due to separation of airflow from the upper surface of the airfoil. •The angle beyond which a ramp or a set of stairs is considered uncomfortable or unsafe. formscritical angles
