libration

[ 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 formsli·bra·tion·al, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for libration

libration

/ (laɪˈbreɪʃən) /

noun

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 Formslibrational, adjective

Word Origin for libration

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