PLIOCENE
Pliocene, Pliocene epoch
(noun) from 13 million to 2 million years ago; growth of mountains; cooling of climate; more and larger mammals
Source: WordNet® 3.1
Etymology
Adjective
Pliocene (not comparable)
(geology) Of a geologic epoch within the Neogene period from about 5.3 to 1.7 million years ago; marked by the appearance of humanity's first ancestors.
Proper noun
Pliocene
(geology) The Pliocene epoch.
Source: Wiktionary
Pli"o*cene, a. [Written also pleiocene.] Etym: [Gr. (Geol.)
Definition: Of, pertaining to, or characterizing, the most recent division
of the Tertiary age.
Pli"o*cene, n. (Geol.)
Definition: The Pliocene period or deposits.
Source: Webster’s Unabridged Dictionary 1913 Edition