WWordGenerator.org GeneratorsWord ListsBlogAboutGenerate a word Home / R / refractive index refractive index noun /rɪfræktɪvɪndɛks/ 4 syllables 16 letters Scrabble 31 WWF 34 Definitions noun the ratio of the velocity of light in a vacuum to that in a medium index of refraction Look “refractive index” up elsewhere Wiktionary ↗ Merriam-Webster ↗ Etymonline ↗ Dictionary.com ↗ Want another word?Spin the dictionary for a fresh one. Generate a word →