The Collaborative International Dictionary of English v.0.48:

Eozoic \E`o*zo"ic\, a. [See Eozo["o]n.] (Geol.)
   Of or pertaining to rocks or strata older than the Paleozoic,
   in many of which the eozo["o]n has been found.
   [1913 Webster]

   Note: This term has been proposed for the strata formerly
         called Azoic, and is preferred especially by those
         geologists who regard the eozo["o]n as of organic
         origin. See Arch[ae]an.
         [1913 Webster]