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

The emission of this thermal radiation acts as a weak thrust that prompts the rotation of the asteroid to speed up — a phenomenon known as the YORP effect (in honor of Yarkovsk, O'Keefe, Radzievskii and Paddack, four scientists who were key to its discovery). —Keith Cooper, Space.com, 27 Jan. 2026

The simplified approach developed by RMIT researchers enables the technology to be deployed near large sources of emissions. —Ameya Paleja, Interesting Engineering, 27 Jan. 2026

Consumers increasingly opt for electric and hybrid vehicles due to concerns over carbon dioxide emissions and fuel efficiency. —Erica Van Buren, USA Today, 27 Jan. 2026

For Connecticut — where state leaders have invested heavily in ports, transmission infrastructure, and clean energy partnerships to drive both economic growth and emissions reductions — the shift raises urgent questions about what comes next. —Bridget Shirvell, Hartford Courant, 26 Jan. 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