[ 'plʌɪstəsi:n ]
■ adjective Geology relating to or denoting the first epoch of the Quaternary period (between the Pliocene and Holocene epochs, from 1.64 million to about 10,000 years ago), a time which included the ice ages and the appearance of humans.
Origin
C19: from Gk pleistos 'most' + kainos 'new'.