index of refraction

noun phrase

Definition of index of refraction 

First Known Use of index of refraction

1829, in the meaning defined above

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The first known use of index of refraction was in 1829

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index of refraction


Medical Definition of index of refraction 

: the ratio of the speed of radiation (as light) in one medium (as a vacuum) to that in another medium

called also refractive index

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a state of commotion or excitement

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