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Meaning of index of refraction

in'dex of refrac'tion

Pronunciation: [key]
— Optics. Optics.
  1. a number indicating the speed of light in a given medium as either the ratio of the speed of light in a vacuum to that in the given mediumor the ratio of the speed of light in a specified medium to that in the given mediumSymbol: n Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.