An Etymological Dictionary of Astronomy and Astrophysics

A phenomenon occurring when a light ray traveling cross
an → interface from a higher → refractive index medium to a lower refractive index medium hits the interface at an angle larger than the → critical angle. In these conditions the light will not pass through to the second → medium at all. Instead, all of it will be reflected back into the first medium.

See also: → total; → internal; → reflection.