Designating, or pertaining to, the earlier periods of the Cenozoic era, or their characteristic formations, between the Mesozoic era and Quaternary period of the Cenozoic, in which the great reptiles had disappeared, the mammals were beginning, and various great ranges, as the Alps, Andes, etc. were forming.

【地】第三纪的；第三系的。

Third in order of time or rank.

第三的；第三级的；第三位的。

The Tertiary period.

【地】第三纪。