- Optics the smallest possible angle of incidence at which light rays are totally reflected
- Aeron. that angle of attack at which the flow of air around an airfoil suddenly changes, with an abrupt reduction in lift and an increase of drag
See critical angle in American Heritage Dictionary 4
- The smallest angle of incidence at which a light ray passing from one medium to another less refractive medium can be totally reflected from the boundary between the two.
- The angle of attack of an airfoil at which airflow abruptly changes, causing changes in the lift and drag of an aircraft.
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