emission

noun

emis·​sion ē-ˈmi-shən 

1

a

: an act or instance of emitting : emanation

b

archaic : publication

c

: a putting into circulation

2

a

: something sent forth by emitting: such as

(1)

: electromagnetic radiation from an antenna or a celestial body

(2)

usually emissions : substances discharged into the air (as by a smokestack or an automobile engine)

b

: effluvium

emissive

ē-ˈmi-siv 

adjective

Examples of emission in a Sentence

trying to reduce the emission of greenhouse gases

Recent Examples on the Web

Steve Hilton, a GOP candidate for governor and former Fox News host, outlined a plan to lower California gas prices to $3 per gallon by slashing regulations including the low-carbon fuel standard, the rule that requires cleaner-burning gas in order to reduce tailpipe emissions. —Los Angeles Times, 17 Mar. 2026

This region is referred to as an active galactic nucleus (AGN), and its bright emissions are seen on Earth as a quasar. —Robert Lea, Space.com, 17 Mar. 2026

Fossil fuels are responsible for up to 68% of greenhouse gas emissions and 90% of carbon dioxide emissions, the United Nations notes. —Julia Jacobo, ABC News, 17 Mar. 2026

Earlier challenge to California emissions authority California has long held special authority under the federal Clean Air Act to set stricter vehicle emissions standards than the federal government because of the state’s historic smog problems. —Madison Smalstig, Sacbee.com, 17 Mar. 2026

Word History

First Known Use

1607, in the meaning defined at sense 1a

Phrases Containing emission

• acoustic emission
• positron-emission tomography
• re-emission
• secondary emission

Rhymes for emission

• addition
• admission
• ambition
• attrition
• audition
• clinician
• cognition
• coition
• commission
• condition
• contrition
• dentition

Kids Definition

emission

noun

emis·​sion ē-ˈmish-ən 

1

: an act or instance of emitting

2

: something emitted or discharged

emissive

ē-ˈmis-iv 

adjective

Medical Definition

emission

noun

emis·​sion ē-ˈmish-ən 

1

: an act or instance of emitting

2

a

: something sent forth by emitting: as

(1)

: electrons discharged from a surface

(2)

: electromagnetic waves radiated by an antenna or a celestial body

(3)

: substances and especially pollutants discharged into the air (as by a smokestack or an automobile gasoline engine)

b

: a discharge of fluid from a living body

especially : ejaculate see nocturnal emission