dynamo – a device that converts mechanical energy into electrical energy in the form of direct current

(pronounced dy-nuh-moh)

To remember the meaning of dynamo, use the following mnemonic:

The dynamite only (dynamo) explodes when an electrical current is switched on by the Disney character (direct current). 

A dynamo is a device that converts mechanical energy (kinetic energy) into electrical energy using electromagnetic induction. It works by a mechanical device rotating a coil of wire within a magnetic field, or by rotating a magnet near a coil of wire. Mechanical devices include hydro electric waterwheels and wind turbines. As the coil or magnet spins, the magnetic field through the coil changes, which induces a current to flow. 

A dynamo produces direct current, which is different to an alternator, a similar device which produces alternating current.