1. A mechanical clock with a pendulum or a balance wheel that is kept in motion by an electromagnetic switch turned on and off regularly by contacts or by an electronic circuit.
2. A clock in which the first wheel of the going train is the rotor of a synchronous electric motor whose speed is entirely controlled by the frequency of the alternating current.
3. Any clock that is operated by electric power; specifically, a clock driven by an alternating-current motor whose current has a definite frequency, controlled at the generator.
4. A clock that is powered by electricity instead of powered manually (winding) or by other sources of energy; specifically, in order to wind the mainspring or to drive the pendulum or oscillator.