'electromagnetic' originates from a modern compound formed in English/New Latin, specifically combining the prefix 'electro-' (from Greek 'ēlektron') where 'ēlektron' meant 'amber' (used for substances producing static electricity) and the element 'magnetic' (from Greek 'magnetēs' via Latin/French) where 'magnetēs' meant 'magnet'.

'electromagnetic' developed in the 19th century from earlier technical coinages such as 'electromagnet' (coined in the early 1800s) and 'electromagnetism'; these compounds led to the established adjective 'electromagnetic' in modern English.

Initially it meant 'pertaining to the combined phenomena of electricity and magnetism'; over time the meaning has remained largely the same but has broadened to include applied contexts (devices, waves, radiation) as well as theoretical descriptions.