re·​frac·​tion ri-ˈfrak-shən How to pronounce refraction (audio)
: 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
: 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
: the action of distorting an image by viewing through a medium
also : an instance of this

Illustration of refraction

Illustration of refraction
  • a light ray
  • b reflected ray
  • c refracted ray

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 number, a sort of impressionistic refraction of a glossy classic-era Hollywood romance, is the high point of the movie’s staging, though not its most inventive sequence. Richard Brody, The New Yorker, 16 Oct. 2023 For Kendall, a sequined limoncello midi dress by Bottega Veneta reflected the spirit of the City of Light, the fabric's refractions mirroring her strappy white sandals and buttery baguette bag in turn. Calin Van Paris, Vogue, 27 June 2023 Unfortunately, the hours will not be split perfectly even due to refraction of sunlight which causes the sun to appear above the horizon when the actual position of the sun is below the horizon. Ellie Willard, The Arizona Republic, 25 July 2023 These telescopes are designed with both lenses and mirrors to show an image, combining refraction and reflection. Jen McCaffery, Popular Science, 21 June 2023 The sound tapers off and eventually stops altogether as shock waves generated by supersonic travel hit the ground and bounce upward, in a process called refraction. Emily Mae Czachor, CBS News, 5 June 2023 The lenses in our mobile devices typically collect and direct incoming light by refraction, using a curve in a transparent material, usually plastic, to bend the rays. IEEE Spectrum, 21 May 2023 Kids will use prisms, spray bottles, and bubbles to learn about refraction and make rainbows. Globe Staff,, 31 May 2023 Armin Doerry, a radar researcher at Sandia National Laboratories, acknowledged this in a 2013 report on the effects of the Earth’s curvature and atmospheric refraction on radar signals. Isabella Fertel, USA TODAY, 8 May 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'refraction.' 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

1603, in the meaning defined at sense 1

Time Traveler
The first known use of refraction was in 1603

Dictionary Entries Near refraction

Cite this Entry

“Refraction.” Dictionary, Merriam-Webster, Accessed 30 Nov. 2023.

Kids Definition


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

Medical Definition


re·​frac·​tion ri-ˈfrak-shən How to pronounce refraction (audio)
: 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
: the refractive power of the eye
: 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

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