in Astrology, persons who erect horoscopes, or pretend to foretell what shall befall a man by means of the stars which presided at his nativity. The word is formed of the Greek γενέσθαι, origin, generation, nativity.

The ancients called them Chaldaeï, and by the general name mathematici: accordingly, the several civil and canon laws, which we find made against the mathematicians, only respect the genethliaci or astrologers.

They were expelled Rome by a formal decree of the senate; and yet found so much protection from the credulity of the people, that they remained therein unmolested. Hence an ancient author speaks of them as hominum genus quod in civitate nostra semper et veletur et retinetur.