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[lahy-brey-shuh n] /laɪˈbreɪ ʃən/
noun, Astronomy
a real or apparent oscillatory motion, especially of the moon.
Origin of libration
1595-1605; < Latin lībrātiōn- (stem of lībrātiō) a balancing. See librate, -ion
Related forms
librational, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for libration
Contemporary Examples
Historical Examples
  • The one on the left illustrates the manner in which the libration in longitude is made apparent.

  • A list of some of the principal astronomical researches of Lagrange and Laplace:—libration of the moon.

    Pioneers of Science Oliver Lodge
  • The last of Galileo's great astronomical discoveries related to the libration of the moon.

    Great Astronomers R. S. Ball
  • We'd show enough, however, to make it damned impressive, and explain it by libration of the satellite.

    Question of Comfort Les Collins
  • The admirable memoir of Lagrange upon the libration of the moon seemed to have exhausted the subject.

  • But it is only an insignificant margin of the far side of the moon which this libration permits us to examine.

    The Story of the Heavens Robert Stawell Ball
  • One more astronomical discovery also he was to make—that of the moon's libration.

    Pioneers of Science Oliver Lodge
British Dictionary definitions for libration


the act or an instance of oscillating
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
Derived Forms
librational, adjective
Word Origin
C17: from Latin librātus, from librāre to balance
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
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