Electromagnetism
Etymology
A compound of "electric" — from Greek "elektron" (amber, which sparks when rubbed) — and "magnet", from the Greek region Magnesia where lodestones were found. Ørsted, Faraday, and finally Maxwell in the 1860s united the two words into one theory that also explained light.
noun · /ih-lek-troh-MAG-neh-tiz-um/
The single force behind both electricity and magnetism, and behind light itself.
What it names
The discovery that electricity and magnetism are not two forces but two faces of one, which is why moving magnets make current and current makes magnets.
Example
Every electric motor, generator, and radio runs on electromagnetism — current and magnetism forever converting into each other.
Related idea
Magnetism alone is just one aspect; electromagnetism is the unified force that ties it to electric charge and to radiation like light and radio, all of which are electromagnetic waves.
See also