Libration

[lai'breiʃәn]

(noun.) (astronomy) a real or apparent slow oscillation of a moon or satellite; 'the libration of the moon'.

戴维斯整理--From WordNet

(n.) The act or state of librating.

(n.) A real or apparent libratory motion, like that of a balance before coming to rest.

阿纳托尔校对