What does emitter mean?
An emitter is anything that gives off or discharges something outward — most commonly a device or material that releases light, heat, radiation, particles, or electronic signals. The word appears frequently across scientific and technical fields: an infrared emitter produces thermal radiation for sensors and remote controls, a beta emitter is a radioactive substance that releases electrons, and a carbon emitter is any source — industrial plant, vehicle, or nation — responsible for releasing carbon dioxide into the atmosphere. In electronics, emitter has a more specific meaning: it names one of the three terminals of a bipolar transistor, the region through which charge carriers exit into the external circuit. The word derives from the Latin emittere, meaning 'to send out', combining ex ('out') with mittere ('to send'). Because it describes a role rather than a specific object, emitter is highly productive in compound phrases and remains essential vocabulary in discussions of technology, energy, and pollution.
nounA device or thing that emits something, such as radiation, light, particles, or signals. In electronics, it also refers to the region of a transistor through which charge carriers flow out.
- A device or substance that gives out light, heat, radiation, particles, or signals.
- In electronics, the electrode or region of a transistor from which charge carriers flow into the external circuit.
"The satellite's infrared emitter scanned the planet's surface for signs of heat."
"The smoke detector contains a tiny alpha emitter that ionises the air inside the chamber."
"By connecting the battery to the base rather than the emitter, the transistor could be switched on and off."
Standard English plural; used when referring to multiple emitting devices, substances, or sources.
"Older power stations remain some of the biggest emitters of sulphur dioxide."
Every glowing LED on your desk is an emitter — and so is every radioactive isotope in the periodic table.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of emitter
Emitter comes from the Latin emittere, meaning 'to send out' or 'to let go', formed from ex- ('out') plus mittere ('to send'). The verb emit entered English in the early 17th century, and emitter developed as its agent noun, denoting that which emits. It shares this Latin root with related words such as emission, emissive, emissary, mission, and transmit.
How emitter is actually used
Emitter is a technical term used primarily in physics, engineering, and environmental science. It carries no strong connotation of praise or criticism in itself, though phrases like 'high emitter' are often used pejoratively in discussions of pollution and climate change. The plural is emitters.
Easily confused with emitter
An omitter is someone who leaves something out, while an emitter is a thing that sends out radiation, particles, or signals.