An Etymological Dictionary of Astronomy and Astrophysics

The latest Epoch of the Tertiary Period, beginning about 5.3 million years ago and ending 1.6 million years ago.

See also: From plio-, varaint of pleo-, from Gk. pleon “more,” cognate with Pers. por, → full, + -cene from Gk. kainos “new, recent.”