/ Dictionary / Index R refractivity: Meaning and Definition of Find definitions for: re•frac•tiv•i•ty Pronunciation: (rē"frak-tiv'i-tē), [key] — n. the power to refract. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: refractivity (Thesaurus) refractive index refractometer Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language