Webster’s Revised Unabridged Dictionary · 1913
Pliocene
Pli′o·cene (plī′ō·sēn), a. [Written also pleiocene.] [Gr. πλείων more + καινός new, recent.] (Geol.) Of, pertaining to, or characterizing, the most recent division of the Tertiary age.
Pli′o·cene, n. (Geol.) The Pliocene period or deposits.