Main Entry: re·frac·tion

Pronunciation: \ri-ˈfrak-shən\

Function: noun

Date: 1603

1 : deflection from a straight path undergone by a light ray or energy wave in passing obliquely from one medium (as air) into another (as glass) in which its velocity is different
2 : the change in the apparent position of a celestial body due to bending of the light rays emanating from it as they pass through the atmosphere; also : the correction to be applied to the apparent position of a body because of this bending
3 : the action of distorting an image by viewing through a medium; also : an instance of this

[refraction illustration]