"to bend or break the natural course of" (light, sound, heat, etc.), 1610s, back-formation from refraction, and in part from Latin refractus, past participle of refringere "to break up," from re- "back" (see re-) + combining form of frangere "to break" (from PIE root *bhreg- "to break"). Related: Refracted; refracting.
word-forming element making adjectives from verbs, meaning "pertaining to, tending to; doing, serving to do," in some cases from Old French -if, but usually directly from Latin adjectival suffix -ivus (source also of Italian and Spanish -ivo). In some words borrowed from French at an early date it has been reduced to -y (as in hasty, tardy).
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Harper, D. (n.d.). Etymology of refractive. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/refractive