| 1. | Also called incidence. Optics, Physics. the angle that a straight line, ray of light, etc., meeting a surface, makes with a normal to the surface at the point of meeting. |
| 2. | (on an airplane) the angle, usually fixed, between a wing or tail root chord and the axis of the fuselage. |
| 3. | Chiefly British. angle of attack (def. 1). |
| 1. | Also called, especially British, angle of incidence. Aeronautics. the acute angle between the chord of an aircraft wing or other airfoil and the direction of the relative wind. |
| 2. | Railroads. the angular attitude of a wheel flange to the rail, esp. on curves. |
| angle of incidence n. The angle formed by a ray incident on a surface and a perpendicular to the surface at the point of incidence. |
| angle of incidence
The angle formed by a ray or wave, as of light or sound, striking a surface and a line perpendicular to the surface at the point of impact. |