An electric violin is a violin

Violin

The violin is a string instrument, usually with four strings tuned in perfect fifths. It is the smallest, highest-pitched member of the violin family of string instruments, which includes the viola and cello....

 equipped with an electronic output of its sound. The term most properly refers to an instrument purposely made to be electrified with built-in pickups, usually with a solid body. It can also refer to a violin fitted with an electric pickup of some type, although "amplified violin" or "electro-acoustic violin" are more accurate in that case.

Electrically amplified violins have been used in one form or another since the 1920s; jazz and blues artist Stuff Smith

Stuff Smith

Hezekiah Leroy Gordon Smith , better known as Stuff Smith, was a jazz violinist. He is known well for the song "If You're a Viper".-Biography:...

 is generally credited as being one of the first performers to adapt pickups and amplifiers to violins.