li·​bra·​tion lī-ˈbrā-shən How to pronounce libration (audio)
: an oscillation in the apparent aspect of a secondary body (such as a planet or a satellite) as seen from the primary object around which it revolves
librational adjective
libratory adjective

Examples of libration in a Sentence

Recent Examples on the Web Based on the new model and Enceladus' libration — relatively large back-and-forth swings during its orbit — the data indicate the moon's ocean is only a few miles beneath the surface. Nathaniel Scharping, Discover Magazine, 4 Oct. 2016 The discovery pivots on the detection of a curious libration—a wobble—in the rotation of Mimas. Jamie Carter, Forbes, 19 Jan. 2022

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'libration.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Latin libration-, libratio, from librare to balance, from libra scales

First Known Use

1667, in the meaning defined above

Time Traveler
The first known use of libration was in 1667

Dictionary Entries Near libration

Cite this Entry

“Libration.” Dictionary, Merriam-Webster, Accessed 23 May. 2024.

More from Merriam-Webster on libration

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!