A musical instrument that produces its sounds using electronics. In contrast, the term electric instrument is used to mean instruments whose sound is produced mechanically, and only amplified or altered electronically - for example an electric guitar. Usually the instrument will have some way of controlling the sound, such as by adjusting the pitch, frequency, or duration of each note.
The most commonly used electronic instruments are synthesizers. Simple electronic musical instruments are sometimes called sound effects; the border between sound effects and actual musical instruments is often hazy.