Merriam-Webster Collegiate Dictionary - electromagnetism

 noun  Date: 1828  1. magnetism developed by a current of electricity  2.  a. a fundamental physical force that is responsible for interactions between charged particles which occur because of their charge and for the emission and absorption of photons, that is about 100 times weaker than the strong force, and that extends over infinite distances but is dominant over atomic and molecular distances — called also electromagnetic force — compare gravity 3a(2), strong force, weak force  b. a branch of physical science that deals with the physical relations between electricity and magnetism