1. autochthonic Aboriginal (L. ab, from, origo, origin) signifies pertaining to the aborigines or earliest known inhabitants of a country in the widest sense, including not merely human beings but inferior a Synonyms: primeval, aboriginal, indigenous, patriarchal, primitive, ancient, native, primal, primordial, autochthonic, old, primary, pristine, immemorial, original, prime, uncreated Antonyms: adventitious, foreign, late, new, recent, exotic, fresh, modern, novel