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A very slow oscillation, real or apparent, of a satellite as viewed from the larger celestial body around which it revolves.

[Latin lībrātiō, lībrātiōn-, oscillation, from lībrātus, past participle of lībrāre, to balance, from lībra, balance.]

li′brate′ (lī′brāt′) v.
li·bra′tion·al adj.
li′bra·to′ry (-brə-tôr′ē) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


1. the act or an instance of oscillating
2. (Astronomy) a real or apparent oscillation of the moon enabling approximately 59 per cent of the surface to be visible from the earth over a period of time
[C17: from Latin librātus, from librāre to balance]
liˈbrational adj
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(laɪˈbreɪ ʃən)

a real or apparent oscillatory motion, esp. of the moon.
[1595–1605; < Latin lībrātiō act of leveling = lībrā(re) to level, balance, derivative of lībra pair of scales + -tiō -tion]
li•bra′tion•al, adj.
li′bra•to`ry (-brəˌtɔr i, -ˌtoʊr i) adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.libration - (astronomy) a real or apparent slow oscillation of a moon or satellite; "the libration of the moon"
astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole
variation - (astronomy) any perturbation of the mean motion or orbit of a planet or satellite (especially a perturbation of the earth's moon)
oscillation - the process of oscillating between states
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in classic literature ?
So, then the moon displays invariably the same face to the earth; nevertheless, to be quite exact, it is necessary to add that, in consequence of certain fluctuations of north and south, and of west and east, termed her libration, she permits rather more than half, that is to say, five-sevenths, to be seen.
DERA ISMAIL KHAN -- A One day seminar was held to commemorate 'Azadi-i- Quds (Libration of Alquds) under the auspices of Tehrik-i-Islami Pakistan here on Thursday.
Zardari said that libration from Indian occupation and exploitation is a basic and democratic right of Kashmiri people.
Yellow dots indicate which part of the Moon's limb is tipped the most toward Earth by libration.
Abdul Hamid was one of the organisers of the 1971 Libration War and close associates of Father of the Nation Bangabandhu Sheikh Mujibur Rahman.
Le prsident de la Rpublique, Abdelaziz Bouteflika, s'est recueilli, mercredi au Carr des Martyrs du cimeti?re d'El Alia (Alger), la mmoire des martyrs de la Guerre de libration nationale, l`occasion de la commmoration du 63?me anniversaire du dclenchement de la Guerre de libration nationale.
Since the launch of the ISEE-3 mission in 1978, the libration points missions have never stopped.
In 2005, Hill suggested placing navigation constellation on the periodic orbits in the vicinity of libration points of the Earth-Moon system to support deep space navigation [6].
Najim al-Jubouri announced libration the left side of Qayyarah district, 45 km south of Mosul.
The topics include laser altimetry and its applications in planetary science, integrating and co-registering multisource Lunar topographic data sets for synergistic use, Martian minerals and rock components from MRO CRISM hyperspectral images, Mercury's magnetic field in the MESSENGER era, determining the Lunar gravity field with data from Chan'E-1 and other missions, and the theory of the physical libration of the Moon with a liquid core.
NNA - Member of Parliament Marwan Hamadeh confirmed on Wednesday that some parliamentary blocs-- mainly "Future", "Lebanese Forces" and "Development and Libration" blocs-- succeeded in penetrating the division between March 14 and March 8 and "are working to approve the salary scale file during the Parliament's legislative session today." "The parliament can't set legislations to the private sector as we are not in a dictatorship or bureaucratic country," the MP explained, separately noting that the bureau committee didn't discuss during its meeting the issue of extending the parliament's term.