n.
Pronunciation: l ī - ' br ā -sh ə n
Function: noun
Etymology: Latin libration-, libratio, from librare to balance, from libra scales
Date: 1667
: an oscillation in the apparent aspect of a secondary body (as a planet or a satellite) as seen from the primary object around which it revolves
– li · bra · tion · al \ -shn ə l, -sh ə -n ə l \ adjective
– li · bra · to · ry \ ' l ī -br ə - ˌ to ̇ r- ē \ adjective