始し生せい代だいしせいだいMeanings1nounArchaeozoic Era; Archeozoic EraGeological term for the early Precambrian era when life first appeared. Used mainly in scientific contexts.始し生せい代だいは約やく40よんじゅう億おく年ねん前まえから25にじゅうご億おく年ねん前まえまでの時じ代だいを