- A control which can be adjusted to set or vary the frequency or frequency response of a component, circuit, device, or instrument, such as a receiver, transmitter, or oscillator.
- A control which is utilized to lock an electronic component onto a chosen frequency. Used, for instance, in TV receivers, radio receivers, and superheterodyne receivers. If automatic, also called automatic frequency control (1).
- A circuit that maintains the frequency of an oscillator within precise limits. Also called automatic frequency control (2).