teatud keraamika, metallide ja sulamite, üleminekugrupi keemiliste ühendite jt omadus spontaalselt anda sisemist magnetilisi momente kindlas suunas, ferromagnetiliste kehade omadus tugevalt ja iseeneslikult magneetuda ning muutuda püsimagnetiks, a property, exhibited by certain ceramics, metals, alloys, and compounds of the transition (iron group), rare earth, and actinide elements, in which the internal magnetic moments spontaneosly organize in a common direction; ther effect gives rise to permeability considerably greater than that of vacuum, and to magnetic hysteresis