parallax

[par-uh-laks]
noun
1.
the apparent displacement of an observed object due to a change in the position of the observer.
2.
Astronomy. the apparent angular displacement of a celestial body due to its being observed from the surface instead of from the center of the earth (diurnal parallax or geocentric parallax) or due to its being observed from the earth instead of from the sun (annual parallax or heliocentric parallax) Compare parallactic ellipse.
3.
the difference between the view of an object as seen through the picture-taking lens of a camera and the view as seen through a separate viewfinder.
4.
an apparent change in the position of cross hairs as viewed through a telescope, when the focusing is imperfect.

Origin:
1585–95; < Greek parállaxis change, equivalent to parallak- (stem of parallássein to cause to alternate, equivalent to para- para-1 + allássein to vary, akin to állos other; see else, allo-) + -sis -sis

parallactic [par-uh-lak-tik] , adjective
parallactically, adverb
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World English Dictionary
parallax (ˈpærəˌlæks)
 
n
1.  an apparent change in the position of an object resulting from a change in position of the observer
2.  astronomy the angle subtended at a celestial body, esp a star, by the radius of the earth's orbit. Annual or heliocentric parallax is the apparent displacement of a nearby star resulting from its observation from the earth. Diurnal or geocentric parallax results from the observation of a planet, the sun, or the moon from the surface of the earth
 
[C17: via French from New Latin parallaxis, from Greek: change, from parallassein to change, from para-1 + allassein to alter]
 
parallactic
 
adj
 
paral'lactically
 
adv

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Etymonline
Word Origin & History

parallax
1580, from M.Fr. parallaxe (1557), from Gk. parallaxis "change, alteration, inclination of two lines meeting at an angle," from parallassein "to alter, make things alternate," from para- "beside" + allassein "to change," from allos "other" (see alias).
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

parallax par·al·lax (pār'ə-lāks')
n.
The apparent displacement of an object caused by a change in the position from which it is viewed.


par'al·lac'tic (-lāk'tĭk) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
parallax   (pār'ə-lāks')  Pronunciation Key 


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An apparent shift in the position of an object, such as a star, caused by a change in the observer's position that provides a new line of sight. The parallax of nearby stars caused by observing them from opposite points in Earth's orbit around the Sun is used in estimating the stars' distance from Earth through triangulation.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Example sentences
When switched on, the parallax barrier controls the direction at which the light leaves the display and the way it hits your eyes.
Also, there isn't really anything great to scale the video with and there could be some parallax errors.
What's interesting is that this distribution compensates for the phenomenon of motion parallax.
The bigger shift creates too great a false parallax, making it tough to resolve.
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