\Re*fract"ive\ (r?*fr?kt"?v), a. [Cf. F.
r['e]fractif. See {Refract}.]
Serving or having power to refract, or turn from a direct
course; pertaining to refraction; as, refractive surfaces;
refractive powers.

{Refractive index}. (Opt.) See {Index of refraction}, under
   {Index}.

{Absolute refractive index} (Opt.), the index of refraction
   of a substances when the ray passes into it from a vacuum.


{Relative refractive index} (of two media) (Opt.), the ratio
   of the sine of the angle of incidence to the sine of the
   angle of refraction for a ray passing out of one of the
   media into the other.