Douglas Harper's Etymology Dictionary
Wiktionary
a. (context physics English) of a material, such as iron or nickel, that is easily magnetized
WordNet
adj. relating to or demonstrating ferromagnetism
Usage examples of "ferromagnetic".
The temperature at which ferromagnetic substances lost their ability to be ferromagnetic (the Curie temperature) varies.
I know there's a good amount of ferromagnetics under us, just from the strength of the magnetic clamps in the suit.
I wondered if silver gave them problems to work, or if it was just the ferromagnetics that did.
Those two, Forester knew, must have found the unity of ferromagnetic and rhodomagnetic and platinomagnetic energies, and discovered the philosophers' stone of mind to shape that prima materia to their desires.
The fourth ferromagnetic element is gadolinium, one of the rare earth metals.
There are thirteen other very similar rare earth metals, but only gadolinium seems to be ferromagnetic.