Eocene (adj.) Look up Eocene at Dictionary.com
in reference to the second epoch of the Tertiary Period, 1831, from eo- "earliest" + Latinized form of Greek kainos "new" (see recent). Coined in English (along with Miocene and Pliocene) by the Rev. William Whewell (1794-1866), English polymath, and meant as "the dawn of the recent." As a noun from 1851.