[adjective] [not gradable], [noun] - (of) the period in the Earth's history which lasted from about 2 000 000 years ago to about 10 000 years ago, during which much of the northern part of the Earth was covered with iceThese are thought to be Pleistocene rocks. It was during the Pleistocene that the earliest humans appeared.
PLEISTOCENE
Meaning of PLEISTOCENE in English
Cambridge English vocab. Кембриджский английский словарь. 2012