libration
Concise Oxford English Dictionary © 2008 Oxford University Press:
libration /lʌɪˈbreɪʃ(ə)n/
▶noun Astronomy an apparent or real oscillation of the moon, by which parts near the edge of the disc that are often not visible from the earth sometimes come into view.
– derivatives
librate verb.
librate verb.
– origin C17: from L. libratio(n-), from librare ‘weigh’, from libra ‘a balance’.
'libration' also found in these Oxford entries:
