a ray approaching a surface.
When dealing with reflection or refraction, the incident ray is the ray of light before it strikes the reflecting or refracting surface.
a ray of light that strikes a surface
An incident ray is a ray travelling towards a surface at which it will be reflected, refracted, scattered or absorbed. Reflecting Light
(of light) A ray of light that strikes a mirror or other optical device.
The name of a ray of light as it enters a diamond, or change of medium.
a ray of light that strikes an object