emission
Americannoun
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an act or instance of emitting.
the emission of poisonous fumes.
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an act or instance of issuing, as paper money.
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Electronics. a measure of the number of electrons emitted by the heated filament or cathode of a vacuum tube.
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an ejection or discharge of semen or other fluid from the body.
- Synonyms:
- ejaculation
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the fluid ejected or discharged.
- Synonyms:
- ejaculate
noun
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the act of emitting or sending forth
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energy, in the form of heat, light, radio waves, etc, emitted from a source
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a substance, fluid, etc, that is emitted; discharge
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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
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physiol any bodily discharge, esp an involuntary release of semen during sleep
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an issue, as of currency
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
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.
Vocabulary lists containing emission
Send a Message: Mit and Miss
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Waves and Wave Properties - Introductory
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Waves and Wave Properties - Middle School
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The incinerator exceeded its emission limits 916 times between 2022 and 2024.
From BBC • Jun. 4, 2026
And last September the head of China’s Ministry of Ecology and Environmentadmitted that “controlling carbon emission intensity is challenging.”
From The Wall Street Journal • May 31, 2026
“This could create serious consequences, including a potential zeroing out of the state’s support for critical emission reduction programs,” said Phillip Fine, executive officer at the Bay Area Air District.
From Los Angeles Times • May 30, 2026
Production ended on July 27, 1990 at a factory in Portugal, precipitated by tightening emission standards in Europe.
From Barron's • May 21, 2026
This system contains two neutron stars orbiting each other, and the energy they are losing by the emission of gravitational waves is causing them to spiral in toward each other.
From "A Brief History of Time: And Other Essays" by Stephen Hawking
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
