1. A phenomenon exhibited by materials like iron (nickel or cobalt) that become magnetized in a magnetic field and retain their magnetism when the field is removed.
2. The property of certain metals and alloys; especially, those of the iron group, rare-earth, and acitinide series, that are capable of spontaneous magnetic polarization, resulting in drastic magnetic effects.

These materials are strongly attracted to magnets and are used in permanent magnets and various ceramic compounds.