1. A falling on or upon; an incident; an event. [Obs.] Bp. Hall. 2. (Physics) The direction in which a body, or a ray of light or heat, falls on any surface. In equal incidences there is a considerable inequality of refractions. Sir I. Newton. Angle of incidence, the angle which a ray of light, or the line of incidence of a body, falling on any surface, makes with a perpendic...
