Pleistocene (adj.)

a name given by geologists to the lower division of the Quaternary, now reckoned as from about 2.6 million years ago and essentially "pertaining to the glacial period," 1839, coined by Lyell from Greek pleistos "most" (superlative of polys "much;" see pleio-) + -cene "recent."

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Definitions of Pleistocene from WordNet

Pleistocene (n.)
from two million to 11 thousand years ago; extensive glaciation of the northern hemisphere; the time of human evolution;
Synonyms: Pleistocene epoch / Glacial epoch