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

“The conditions encourage speed. Removing the source of the odors is the primary objective here. However, that speed should not come at the detriment of the emission of odors or public health.”

From Los Angeles Times ● Aug. 6, 2026

A source dominated by accelerated electrons would generally be expected to produce stronger X-ray signals, so the faint emission further supported the proton explanation.

From Science Daily ● Aug. 2, 2026

The changes would mean some industries could obtain emission allowances until 2038 instead of 2034, if they commit to investing in decarbonisation efforts.

From BBC ● Jul. 17, 2026

Dutch peer Royal Philips doesn’t compete in radio-oncology or positron emission tomography, but it is already seeing pressure through centralized procurement of ultrasound equipment, the analysts say.

From The Wall Street Journal ● Jul. 15, 2026

At this distance it would still be very difficult to detect the steady emission of a black hole, even if it was ten thousand megawatts.

From "A Brief History of Time: And Other Essays" by Stephen Hawking

Nuclear power produces no greenhouse gas emissions, the primary driver of climate change.

From Los Angeles Times ● Aug. 16, 2026

The findings also raise the possibility that lowering emissions could have an additional role in protecting long-term human health.

From Science Daily ● Aug. 15, 2026

Officials said other benefits of minimising outdoor lighting included lower carbon emissions and energy costs.

From BBC ● Aug. 14, 2026

The UK has set a target to consume zero-carbon electricity by 2030 and is aiming to reach net-zero greenhouse gas emissions by 2050 to combat climate change.

From Barron's ● Aug. 14, 2026

The study concluded that the effect on Americans of radioactive emissions from nuclear tests was vastly outweighed by their exposure to diagnostic X-rays and other common sources.

From "Big Science" by Michael Hiltzik

Related Words

• discharge
• radiation