CAEMENTARIUS Latin. A builder of walls, a mason, from caemantum, a rough, unhewn stone as it comes from the quarry. In medieval Latin, the word is used to designate an Operative Mason. Du Cange cites Magister Caementariorum as used to designate him who presided over the building of edifices, that is, the Master of the works. It has been adopted by some modern writers as a translation of the word Freemason. Its employment for that purpose is perhaps more correct than that of the more usual word latomus, which owes its use to the authority of Thory.