refractive index


: the ratio of the speed of radiation (such as light) in one medium (such as air, glass, or a vacuum) to that in another medium

Examples of refractive index in a Sentence

Recent Examples on the Web The refractive index is directly related to the concentration of chemical constituents within the cells, such as DNA, proteins and lipids. Matjaž Humar and Seok-Hyun Yun, Discover Magazine, 27 July 2015 Finally, Noda’s group dealt with the problem of heat altering the device’s refractive index and causing the beam to diverge. IEEE Spectrum, 20 June 2023 So his description involves this idea of index matching, where the refractive index of light has to be perfectly matched between the invisible object and the stuff around it. Jennifer Ouellette, Ars Technica, 17 July 2023 This skeleton is still opaque, because the cell walls bend light to a different degree than the air in the cell pockets does—a value called a refractive index. Jude Coleman, Smithsonian Magazine, 19 Dec. 2023 In a typical photonic crystal laser, the holes—which have a different refractive index from the surrounding semiconductor—cause light within the laser to deflect in a precise way. IEEE Spectrum, 20 June 2023 Furthermore, if the laser is operating continuously, heat inside the laser changes the device’s refractive index, causing the beam’s quality to deteriorate even further. IEEE Spectrum, 20 June 2023 The laser pulses can alter the refractive index of the air—the quality of a material that controls how quickly light travels within it. IEEE Spectrum, 31 Dec. 2022 Seager and co also point out that microbial cells would change the refractive index (and therefore the apparent shape) of these droplets. The Physics Arxiv Blog, Discover Magazine, 16 Dec. 2021

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'refractive index.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1839, in the meaning defined above

Time Traveler
The first known use of refractive index was in 1839

Dictionary Entries Near refractive index

Cite this Entry

“Refractive index.” Dictionary, Merriam-Webster, Accessed 20 Apr. 2024.

Kids Definition

refractive index

: the ratio of the speed of light in one medium (as air or glass) to that in another medium

Medical Definition

refractive index


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