archæo-|ˌɑːkiːəʊ-|ad.Gr. ἀρχαιο- comb. form of ἀρχαῖος ancient, primitive (f. ἀρχή beginning). Formerly, and still occas., spelt archaio-. In compounds and derivatives, as archæology; also: archæo-geˈology, the geology of ancient periods of the earth's history. archæoˈlithica.[λίθος stone], of or pertaining to the most ancient stone implements used by prehistoric man. archæoˈstomatousa.[στόµα mouth], having the primitive orifice of invagination of the wall of the embryo persistent as a mouth. archæoˈzoica.[ζωή life], pertaining to the era of the earliest living beings on our planet.1877Shields Final Philos. 143 Archæo-geology..has ventured still further backward through the past organic epochs.1865Lubbock Preh. Times 60 The period of the drift, which I have proposed to call the archæolithic period.1877Huxley Anat.Inv. An. xii. 684 The limits within which the archæostomatous condition prevails.1872Dana CoralsApp. I. 373 The era..styled the Archeozoic.