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 ]

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 ]