The Collaborative International Dictionary of English v.0.48:

Archaeozoic \Archaeozoic\ n. [Gr. 'archai^os ancient + zw^,on
   animal.]
   the time from 1.5 billion to 5 billion years ago; the time
   when the earth's crust formed; a time when only unicellular
   organisms and the earliest forms of life are present.

   Syn: Archeozoic, Archeozoic era, Archaeozoic era
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

archaeozoic \archaeozoic\, Archaeozoic \Ar`ch[ae]*o*zo"ic\, a.
   [Gr. 'archai^os ancient + zw^,on animal.] (Zool.)
   Like or belonging to the earliest forms of animal life.
   [1913 Webster]

   2. (Geol.) formed in or belonging to the earlier of two
      divisions of the Precambrian era. archaeozoic life forms

   Syn: archeozoic
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

archaeozoic
    adj 1: of or belonging to earlier of two divisions of the
           Precambrian era; "archeozoic life forms" [syn:
           archeozoic, archaeozoic]
    n 1: the time from 3,800 million years to 2,500 million years
         ago; earth's crust formed; unicellular organisms are
         earliest forms of life [syn: Archean, Archean eon,
         Archean aeon, Archeozoic, Archaeozoic, Archeozoic
         eon, Archaeozoic aeon]