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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. 2018.
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Examples from the Web for libration
Contemporary Examples
Historical Examples
  • A list of some of the principal astronomical researches of Lagrange and Laplace:—libration of the moon.

    Pioneers of Science Oliver Lodge
  • The one on the left illustrates the manner in which the libration in longitude is made apparent.

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

    Great Astronomers R. S. Ball
  • One more astronomical discovery also he was to make—that of the moon's libration.

    Pioneers of Science Oliver Lodge
  • 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
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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