libratory


li·bra·tion

L0151500 (lī-brā′shən)n. A very slow oscillation, real or apparent, of a satellite as viewed from the larger celestial body around which it revolves.
[Latin lībrātiō, lībrātiōn-, oscillation, from lībrātus, past participle of lībrāre, to balance, from lībra, balance.]
li′brate′ (lī′brāt′) v.li·bra′tion·al adj.li′bra·to′ry (-brə-tôr′ē) adj.