1. The loadstone; a species of iron ore (the ferrosoferric or magnetic ore, Fe3O4) which has the property of attracting iron and some of its ores, and, when freely suspended, of pointing to the poles; called also natural magnet. Dinocrates began to make the arched roof of the temple of Arsinoe all of magnet, or this loadstone. (Holland) Two magnets, heaven and earth, allure to bliss, The larger loadstone that, the nearer this. (Dryden)
(Science: physics) field magnet, a magnet used for producing and maintaining a magnetic field; used especially of the stationary or exciting magnet of a dynamo or electromotor in distinction from that of the moving portion or armature.