Re‐fract″ive (r?‐fr?kt″?v), a. [Cf. F. réfractif. 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.