9 results for: Parallax

Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This

par·al·lax

Audio Help [par-uh-laks] Pronunciation Key

–noun

1.	the apparent displacement of an observed object due to a change in the position of the observer.

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; < Gk parállaxis change, equiv. to parallak- (s. of parallássein to cause to alternate, equiv. to para- para-¹ + allássein to vary, akin to állos other; see else, allo-) + -sis -sis

]

—Related forms

par·al·lac·tic

Audio Help [par-uh-lak-tik] Pronunciation Key, adjective

par·al·lac·ti·cal·ly, adverb

Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.

Encyclopædia Britannica, Inc.
Parallax

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American Heritage Dictionary - Cite This Source - Share This

par·al·lax Audio Help (pār'ə-lāks') Pronunciation Key

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n. An apparent change in the direction of an object, caused by a change in observational position that provides a new line of sight.

[French parallaxe, from Greek parallaxis, from parallassein, to change : para-, among; see para-¹ + allassein, to exchange (from allos, other; see al-¹ in Indo-European roots).]

par'al·lac'tic (-lāk'tĭk) adj.

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The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2006 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.

Online Etymology Dictionary - Cite This Source - Share This
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).

WordNet - Cite This Source - Share This

parallax
noun
the apparent displacement of an object as seen from two different points that are not on a line with the object

The American Heritage Science Dictionary - Cite This Source - Share This

parallax Audio Help (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 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.

American Heritage Stedman's Medical Dictionary - Cite This Source - Share This

par·al·lax (pr-lks)
n.

The apparent displacement of an object caused by a change in the position from which it is viewed.

paral·lactic (-l

k) adj.

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

Merriam-Webster's Medical Dictionary - Cite This Source - Share This

Main Entry: par·al·lax
Pronunciation: 'par-&-"laks
Function: noun
: the apparent displacement or the difference in apparent direction of an object as seen from two different points not on a straight line with the object <our two eyes are as a rule only about 2¹/₄ inches apart; yet the small parallax caused by the slightly different angle of vision enables us to see three-dimensional, plastic images and to judge distances accurately —Erwin Raisz>

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Parallax

Di*ur"nal\, a. [L. diurnalis, fr. dies day. See Deity, and cf. Journal.]

1. Relating to the daytime; belonging to the period of daylight, distinguished from the night; -- opposed to nocturnal; as, diurnal heat; diurnal hours.

2. Daily; recurring every day; performed in a day; going through its changes in a day; constituting the measure of a day; as, a diurnal fever; a diurnal task; diurnal aberration, or diurnal parallax; the diurnal revolution of the earth.

Ere twice the horses of the sun shall bring Their fiery torcher his diurnal ring. --Shak.

3. (Bot.) Opening during the day, and closing at night; -- said of flowers or leaves.

4. (Zo["o]l.) Active by day; -- applied especially to the eagles and hawks among raptorial birds, and to butterflies (Diurna) among insects.

Diurnal aberration (Anat.), the aberration of light arising from the effect of the earth's rotation upon the apparent direction of motion of light.

Diurnal arc, the arc described by the sun during the daytime or while above the horizon; hence, the arc described by the moon or a star from rising to setting.

Diurnal circle, the apparent circle described by a celestial body in consequence of the earth's rotation.

Diurnal motion of the earth, the motion of the earth upon its axis which is described in twenty-four hours.

Diurnal motion of a heavenly body, that apparent motion of the heavenly body which is due to the earth's diurnal motion.

Diurnal parallax. See under Parallax.

Diurnal revolution of a planet, the motion of the planet upon its own axis which constitutes one complete revolution.

Syn: See Daily.

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