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Refraction

 - 6 dictionary results

re⋅frac⋅tion

[ri-frak-shuhn]
–noun
1. Physics. the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different.
2. Ophthalmology.
a. the ability of the eye to refract light that enters it so as to form an image on the retina.
b. the determining of the refractive condition of the eye.
3. Astronomy.
a. Also called astronomical refraction. the amount, in angular measure, by which the altitude of a celestial body is increased by the refraction of its light in the earth's atmosphere, being zero at the zenith and a maximum at the horizon.
b. the observed altered location, as seen from the earth, of another planet or the like due to diffraction by the atmosphere.

Origin:
1570–80; < LL refrāctiōn- (s. of refrāctiō). See refract, -ion


re⋅frac⋅tion⋅al, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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re·frac·tion   (rĭ-frāk'shən)   


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n.  
  1. The turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another of different optical density.

  2. Astronomy The apparent change in position of celestial objects caused by the bending of light rays entering Earth's atmosphere.

  3. Medicine

    1. The ability of the eye to bend light so that an image is focused on the retina.

    2. Determination of the refractive characteristics of the eye.

re·frac'tion·al, re·frac'tive adj., re·frac'tive·ly adv., re·frac'tive·ness, re'frac·tiv'i·ty (rē'frāk-tĭv'ĭ-tē) n.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Cultural Dictionary

refraction

A change of direction that light undergoes when it enters a medium with a different density from the one through which it has been traveling — for example, when, after moving through air, it passes through a prism. (Compare reflection.)

Note: Lenses and other optical instruments work through refraction of light.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Word Origin & History

refraction 
1578, from L.L. refractionem (nom. refractio) "a breaking up," from L. refractus, pp. of refringere "to break up," from re- "back" + comb. form of frangere "to break" (see fraction). Refractory "stubborn, obstinate, perverse" is attested from 1613 (earlier refractorious, 1555), from L. refractarius "obstinate." Refrangible first recorded 1673.
Online Etymology Dictionary, © 2001 Douglas Harper
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Medical Dictionary

Main Entry: re·frac·tion
Pronunciation: ri-'frak-sh&n
Function: noun
1 : the deflection from a straight path undergone by a lightray 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
2 a : 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
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

refraction re·frac·tion (rĭ-frāk'shən)
n.

  1. The turning or bending of any wave, such as a light or sound wave, when it passes from one medium into another of different density.

  2. The ability of the eye to bend light so that an image is focused on the retina.

  3. Determination of the refractive characteristics of the eye and often the correction of refractive defects with lenses. Also called refringence.


re·frac'tion·al or re·frac'tive adj.
re·frac'tive·ness or re'frac·tiv'i·ty (rē'frāk-tĭv'ĭ-tē) n.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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