Oligocene
adjective
Ol·i·go·cene ˈä-li-gō-ˌsēn 
ˈō-
ˈō- ə-ˈli-gə-
: of, relating to, or being an epoch of the Tertiary between the Eocene and Miocene or the corresponding series of rocks see Geologic Time Table
Oligocene noun
Word History
Etymology
borrowed from German Oligocän (now Oligozän), from oligo- oligo- + -cän -cene
Note: The term was introduced by the German geologist Heinrich Ernst Beyrich (1815-96) in a report "on the position of the Hessian tertiary formations" ("über die Stellung der Hessischen Tertiärbildungen") read to the Physical-Mathematical Class of the Royal Prussian Academy of Sciences, Berlin, on November 27, 1854 (published in Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlichen Preussischen Akademie der Wissenschaften zu Berlin aus dem Jahre 1854, p. 664).
First Known Use
circa 1859, in the meaning defined above