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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Did You Know?

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

This light bending, or refraction, degrades the quality of the image, especially to the left and right of the scanner’s light source. Scientific American, "Test Pilot Geese, Planetary Wrecking Balls and Super AI Vision: The Week’s Best Science GIFs," 6 Sep. 2019 The agency’s enforcement action, taken earlier this month, involved Visibly’s Online Refractive Vision Test, used to measure vision refraction. Lisa Schencker,, "Chicago company’s online vision test gets pulled by FDA in win for eye doctors," 28 Aug. 2019 Akerman, who died in 2015, is one of the pioneers of the personal cinema, of the candid refraction of first-person experience into drama, into documentary—and into audacious reconceptions of these cinematic forms themselves. Richard Brody, The New Yorker, "What to Stream: A Rediscovered Short by—and Starring—Chantal Akerman," 22 Aug. 2019 In certain situations, refraction can focus a huge amount of light on a small area, erasing the need for a giant structure to catch it all. Leila Sloman, Scientific American, "Earth Could Be a Lens for a Revolutionary Space Telescope," 14 Aug. 2019 The trick of the lensmaker’s art is to grind the two surfaces into such shapes that the sum of all this refraction brings the light passing through the lens to a focus. The Economist, "How to make a flat lens," 25 July 2019 Alas, none of these reflections and refractions of Gershwin’s work are even mentioned by Crawford as an insight into the composer’s immense influence. Laurence Maslon, Washington Post, "The thoroughly modern genius of George Gershwin," 6 Sep. 2019 Some other graphical improvements coming to Minecraft, thanks to ray tracing, include direct lighting from the sun, more realistic shadows, and transparent materials like stained glass and water with reflection and refraction effects. Nick Statt, The Verge, "Minecraft will get ray tracing for Nvidia RTX graphics cards," 19 Aug. 2019 In the funhouse-mirror refractions of the pool, a woman’s body may be viewed in a new light. Amanda Hess, New York Times, "Women Crash the Pool Party," 3 July 2019

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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Statistics for refraction

Last Updated

13 Oct 2019

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Time Traveler for refraction

The first known use of refraction was in 1603

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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

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More from Merriam-Webster on refraction

Rhyming Dictionary: Words that rhyme with refraction

Spanish Central: Translation of refraction

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

Comments on refraction

What made you want to look up refraction? Please tell us where you read or heard it (including the quote, if possible).


to wander slowly or to speak indistinctly

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