Emitter (noun)

A device or substance that emits or gives off something, such as radiation or light.

Origin:

Early 20th century: from latin emittere "send out".

Examples:

1. A light bulb is an emitter of light.
2. A radio transmitter is an emitter of radio waves.
3. An emitter is a device that sends out energy.
4. An emitter can be a physical object or a chemical substance.
5. An emitter can be a source of light, heat, sound, or other forms of energy.