Main Entry: re·frac·tion

Pronunciation: \ri-ˈfrak-shən\

Function: noun

1 : the deflection from a straight path undergone by a light ray or a wave of energy in passing obliquely from one medium (as air) into another (as water or glass) in which its velocity is different
2 a : the refractive power of the eye b : the act or technique of determining ocular refraction and identifying abnormalities as a basis for the prescription of corrective lenses