1. A device for converting alternating current to direct current or vice versa.
2. A device that changes the frequency of a signal; a frequency changer.
3. A device, such as an impedance converter, that has different electrical properties at its input and output and may be used to couple dissimilar circuits.
4. A device, such as a compiler, that changes an information code.
5. A transducer that converts energy of one type, such as sound waves or electromagnetic radiation, into electrical energy.