Any musical instrument where the sound is generated by electrical or electronic means.

The category was added to the Hornbostel-Sachs musical instrument classification system in 1940, to cover instruments involving electricity, with 3 subcategories:

• electrically-actuated acoustic instruments (such as a pipe organ with electronic tracker action)
• electrically-amplified acoustic instruments (such as an acoustic guitar with pickup)
• instruments which make sound primarily by way of electrically-driven oscillators (such as a theremin or synthesiser)

However, modern thinking is that electrophones should only include instruments which produce sound primarily by electrical means. Hence, an electric guitar, for example, would remain as a chordophone.