Electro-magnetic \E*lec`tro-mag*net"ic\, a. Of, Pertaining to, or produced by, magnetism which is developed by the passage of an electric current.

Electro-magnetic engine, an engine in which the motive force is electro-magnetism.

Electro-magnetic theory of light (Physics), a theory of light which makes it consist in the rapid alternation of transient electric currents moving transversely to the direction of the ray.

Source: Webster's Revised Unabridged Dictionary (1913)