re·​frac·​tion | \ ri-ˈfrak-shən How to pronounce refraction (audio) \

Definition of refraction

1 : deflection from a straight path undergone by a light ray or energy wave in passing obliquely from one medium (such as air) into another (such as glass) in which its velocity is different
2 : the change in the apparent position of a celestial body due to bending of the light rays emanating from it as they pass through the atmosphere also : the correction to be applied to the apparent position of a body because of this bending
3 : the action of distorting an image by viewing through a medium also : an instance of this

Illustration of refraction

Illustration of refraction

refraction 1: a light ray, b reflected ray, c refracted ray

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The root of refraction is seen in the notion that the path of a ray of light or wave of energy is "broken" when it is deflected or turned. The effects of refraction can be seen in a rainbow, which is formed when light rays passing into (and reflecting out of) water droplets are bent at different angles depending on their color, so that the light separates into bands of color. The amount of refraction depends on the angle and the type of matter; refraction can occur even when passing through different kinds of air. A mirage, such as you might see in the desert or over a patch of asphalt in the summer, occurs when light passing through warm air meets the very hot air near the surface; reflecting the sky, it often resembles a lake.

Examples of refraction in a Sentence

Recent Examples on the Web Their eyes showed 59% less progression away from ideal refraction and 52% less growth of eye length. Fortune, 12 Jan. 2022 But light refraction isn't all that diamonds do, says co-founder and co-CEO Tata Harper. Beatrice Hazlehurst, Allure, 7 Dec. 2021 In the shadow and the angle the light hits the Earth, a process called Rayleigh scattering occurs, which is basically the refraction of light. Rick Green,, 19 Nov. 2021 During a night hike in the tropics of Borneo, the photographer observed a bracket fungus releasing masses of spores which caused the refraction of light, while a cockroach feeds. Cecilia Rodriguez, Forbes, 25 Oct. 2021 This bouncing or bending of light's trajectory, known as refraction, causes any astronomical object to appear to its observers as higher up in the sky than its true geometric location. Miriam Fauzia, USA TODAY, 25 Sep. 2021 Of the two processes, refraction plays a particularly important role in the formation of rainbows., 4 Aug. 2021 The story that follows is a kind of Chaucerian refraction of the vicious military assault that shocked the world in 1989. Washington Post, 11 Aug. 2021 In addition to the waves, many boaters fail to anticipate the refraction caused by the wake of the boats in front of them., 15 July 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'refraction.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of refraction

1603, in the meaning defined at sense 1

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Time Traveler for refraction

Time Traveler

The first known use of refraction was in 1603

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Dictionary Entries Near refraction

refracting telescope


refraction angle

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Statistics for refraction

Last Updated

22 Jan 2022

Cite this Entry

“Refraction.” Dictionary, Merriam-Webster, Accessed 28 Jan. 2022.

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More Definitions for refraction


re·​frac·​tion | \ ri-ˈfrak-shən How to pronounce refraction (audio) \

Kids Definition of refraction

: the bending of a ray when it passes at an angle from one medium into another in which its speed is different (as when light passes from air into water)


re·​frac·​tion | \ ri-ˈfrak-shən How to pronounce refraction (audio) \

Medical Definition of refraction

1 : the deflection from a straight path undergone by a light ray or a wave of energy in passing obliquely from one medium (as air) into another (as water or glass) in which its velocity is different
2a : the refractive power of the eye
b : the act or technique of determining ocular refraction and identifying abnormalities as a basis for the prescription of corrective lenses

More from Merriam-Webster on refraction

Nglish: Translation of refraction for Spanish Speakers Encyclopedia article about refraction


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