What does emission mean?
Emission refers to the act or process of sending out or discharging something into the environment — whether gas, light, heat, sound, or radiation — as well as the substance so released. Derived from the Latin emittere, meaning 'to send out', it entered English in the early seventeenth century. In contemporary usage the word is dominated by environmental discourse: phrases like 'carbon emissions' and 'greenhouse gas emissions' appear constantly in news coverage, policy documents, and everyday conversation about climate change. In these contexts 'emission' typically takes a plural form, treating pollutants collectively rather than individually. Beyond ecology, the term retains precise scientific applications: physicists speak of the emission of photons or particles, engineers of exhaust emissions from engines, and astronomers of electromagnetic emissions from stars. The word is neutral and formal in register, though its frequent pairing with pollution gives it a mildly negative connotation in general use. Its derivatives include the verb emit and the noun emitter.
nounThe act or process of discharging something — such as gas, light, heat, sound, or radiation — into the surrounding environment. It also refers to the substance that is discharged, most commonly in discussions of pollution and greenhouse gases.
- The discharge of gas, radiation, or other substances into the environment, especially pollutants or greenhouse gases.
- The act of emitting light, heat, sound, or particles (as in physics).
- Something that has been emitted; a discharge or release.
- (Physiology) The involuntary discharge of semen, especially during sleep (nocturnal emission).
"The new regulations aim to cut carbon emissions from power plants by half within a decade."
"The government pledged to reduce greenhouse gas emissions by 40 percent before 2035."
"The detector measures the emission of alpha particles from the sample."
'Emissions' is the overwhelmingly common form when referring to pollutants or greenhouse gases collectively; the singular 'emission' is preferred for a single act of discharge or in physics contexts.
"Stricter emissions standards forced manufacturers to redesign their engines."
The word 'emission' comes from Latin emittere, 'to send out' — and today it's the single word around which global climate policy revolves.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of emission
Emission derives from the Latin emittere, formed from e- ('out') and mittere ('to send'), via the past participle emissio, 'a sending out'. It entered English in the early seventeenth century, initially in scientific and medical contexts before broadening to cover any discharge of matter or energy. It shares this Latin root with related words such as emissary, mission, and remission, all built on mittere.
Related word forms
How emission is actually used
In everyday and journalistic use, 'emission' almost always appears in its plural form when referring to pollutants ('carbon emissions', 'vehicle emissions'), even for gases as a mass concept. The singular is more common in technical physics contexts. The term carries a strongly environmental connotation in modern usage.
Easily confused with emission
An emission is something sent out or discharged, while an omission is something left out or neglected to be done.
Immersion means being plunged into or absorbed within a medium, whereas emission means being discharged outward.