Mid 17th century (in an earlier sense). As noun from post-classical Latin astromanticus, use as noun of astromanticus, adjective; as adjective from post-classical Latin astromanticus or its etymon Hellenistic Greek ἀστρομαντικός (only attested in ἀστρομαντική (feminine singular noun, short for ἀστρομαντικὴ τέχνη astromantic art) astrology) from ἀστρόμαντις astrologer + -ικός.