libration
nounUK, US /laɪˈbɹeɪ.ʃən/
Etymology From Latin lībrātiō (“a hurling, swinging”), from lībrō (“poise, cause to swing”).
1
The act of librating.
2
Astronomy, Natural sciences The apparent wobble or variation in the visible side of the Moon that permanently faces the Earth, allowing observers on Earth to see, over a period of time, slightly more than half of the lunar surface.
3
Broadly A similar rotational or orbital characteristic of some other celestial body.
4
The oscillation of an angle about a stable equilibrium point.
5
Chemistry, Natural sciences, Physical sciences A vibrational degree of freedom whereby a group of atoms partly rotates back and forth, similar to the Moon's motion.
6
Figuratively A wavering between two opposing thoughts or choices.
- We may not quarrel with attempts to picture the libration of emotion which sways Clytaemestra as she veers from love for her husband to the desire to take vengeance upon him[…]1924, Herbert Weir Smyth, “VI. Orestea. I: Agamemnon”, in Aeschylean Tragedy, page 175:
- Derived terms
- antilibration, librational, libration point