Electro-magnet n. : A mass, usually of soft iron, but sometimes of some other magnetic metal, as nickel or cobalt, rendered temporarily magnetic by being placed within a coil of wire through which a current of electricity is passing. The metal is generally in the form of a bar, either straight, or bent into the shape of a horseshoe.

Example:
what is the different between electro magnet and magnet?

Taxonomy
electromagnet, magnetic field, windings, magnet, wire, Bitter electromagnet, core material, coil, iron, air gap, pole, magnetic circuit, energy, Uses of electromagnets, Superconducting magnets, the electromagnets, proportional, iron core.

Defination from the web:
magnet that the field lines emerge from is defined to be the north pole. ... Improved Electro Magnetic Apparatus". Trans. Royal Society of Arts, Manufactures, & Commerce (London) 43: 37–52. cited in Miller, T.J.E (2001) ...