[ ih-lawng-gey-shuhn, ih-long-, ee-lawng-, ee-long- ]
/ ɪ lɔŋˈgeɪ ʃən, ɪ lɒŋ-, ˌi lɔŋ-, ˌi lɒŋ- /
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the act of elongating or the state of being elongated.
something that is elongated.
Astronomy. the angular distance, measured from the earth, between a planet or the moon and the sun or between a satellite and the planet about which it revolves.



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Origin of elongation

1350–1400; Middle English <Late Latin ēlongātiōn- (stem of ēlongātiō), equivalent to ēlongāt(us) (see elongate) + -iōn--ion
non·e·lon·ga·tion, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for elongation

/ (ˌiːlɒŋˈɡeɪʃən) /


the act of elongating or state of being elongated; lengthening
something that is elongated
astronomy the difference between the celestial longitude of the sun and that of a planet or the moon
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for elongation

[ ĭ-lông′gāshən ]

The angular distance between two celestial bodies as seen from a third. Elongation is normally conceived as a measure of the angle formed between the Sun and a celestial body, such as a planet or the Moon, with Earth at the vertex. In terms of the celestial sphere, elongation is the distance between the Sun and the body as measured in degrees of celestial longitude. When the body lies on a direct line drawn from Earth to or through the Sun, its elongation is 0° and it is said to be in conjunction. It is said to be in quadrature when it lies at a right angle to a line between the Earth and Sun with an elongation of 90°, and it is in opposition when it lies on the opposite side of Earth from the Sun with an elongation of 180°. Superior planets (those that are farther from the Sun than Earth) have a full range of elongations between 0° and 180°. Inferior planets (those closer to the Sun than Earth) have limited elongations due to their smaller orbits; Venus has a greatest elongation of about 48°, while Mercury's greatest elongation is about 28°. See more at conjunction opposition.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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