emission

American  

[ih-mish-uhn] / ɪˈmɪʃ ən /

noun

• emissions
  plural

1. an act or instance of emitting.

   the emission of poisonous fumes.

2. something that is emitted; discharge; emanation.

3. an act or instance of issuing, as paper money.

4. Electronics. a measure of the number of electrons emitted by the heated filament or cathode of a vacuum tube.

5. an ejection or discharge of semen or other fluid from the body.

   Synonyms:

   ejaculation

6. the fluid ejected or discharged.

   Synonyms:

   ejaculate

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emission British  

/ ɪˈmɪʃən /

noun

1. the act of emitting or sending forth

2. energy, in the form of heat, light, radio waves, etc, emitted from a source

3. a substance, fluid, etc, that is emitted; discharge

4. a measure of the number of electrons emitted by a cathode or electron gun See also secondary emission thermionic emission

   at 1000°C the emission is 3 mA

5. physiol any bodily discharge, esp an involuntary release of semen during sleep

6. an issue, as of currency

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Usage

What does emission mean? An emission is something that has been emitted—released or discharged. In general, emissions consist of things like gas, liquid, heat, sound, light, and radiation. Emissions can come from natural sources or from machines. A specific example of an emission is the exhaust from cars (in the U. S., such emissions are regulated through emissions tests). This exhaust is just one form of carbon emissions—greenhouse gases from various sources that are known to contribute to global warming and climate change. Emission can also refer to an instance or the process of emitting, as in This filter is designed to reduce the emission of light. Example: Carbon dioxide emissions from volcanoes are much lower than those from cars and airplanes.

Other Word Forms

Derived Forms

• nonemission
  noun
• reemission
  noun
• emissive
  adjective

Inflected Forms

Nouns

• emissions
  plural

Etymology

Origin of emission

First recorded in 1600–10; from Middle French or directly from Latin ēmissiōn- (stem of ēmissiō ), equivalent to ēmiss(us), past participle of ēmittere “to send forth” ( ē- “from, out of” + mit-, stem of mittere “to send” + -tus past participle suffix) + -iōn- noun suffix; see origin at emit, e- ¹, -ion

Explanation

An emission is something that's been released or emitted into the world. Car exhaust, burps, and radio broadcasts are all examples of emissions. Technically, an emission is anything that's been released out into the open. But more often it refers to gases being released into the air, like greenhouse gasses or emissions from power plants and factories. Anytime your body emits something (sweat, drool, gas), it's also considered an emission. Be careful not to confuse this word with the closely spelled omission — that's something that's been left out.

Example Sentences

See Examples For:

emission emissions

In contrast, Einstein Probe recorded bright X-ray emission for nearly ten minutes.

From Science Daily ● Sep. 30, 2026

Neutral hydrogen naturally gives off a very weak radio emission known as the 21-centimeter line.

From Science Daily ● Sep. 9, 2026

That’s because auto makers equip new models with ultra-low drag tires to meet fuel economy and emission standards in labs.

From The Wall Street Journal ● Aug. 23, 2026

SpaceXAI, which did not respond to a request for comment, said in a statement that it is working to make sure that its mobile turbines are "equipped with advanced emission control technologies."

From Barron's ● Aug. 11, 2026

That Jupiter is a source of radio emission was discovered accidentally in the 1950’s, the early days of radio astronomy.

From "Cosmos" by Carl Sagan

The air board started working with Carbon Mapper last spring to pinpoint methane emissions.

From Los Angeles Times ● Oct. 1, 2026

But researchers stress that sharp cuts to carbon emissions can still save much of the world's glacier ice.

From BBC ● Oct. 1, 2026

The continent's widespread emissions are driven by industrialisation, economic development and transport, as well as wildfires and the burning of agricultural residue.

From Barron's ● Sep. 30, 2026

“What the industry needs is long-term regulatory stability that includes balanced, durable and achievable fuel economy standards that continue to reduce emissions and improve fuel economy,” the Alliance for Automotive Innovation said.

From The Wall Street Journal ● Sep. 28, 2026

But it’s trees that clean carbon emissions and provide oxygen.”

From "Paradise on Fire" by Jewell Parker Rhodes

Related Words

• discharge
• radiation