: a fog made heavier and darker by smoke and chemical fumes
also
: a photochemical haze caused by the action of solar ultraviolet radiation on atmosphere polluted with hydrocarbons and oxides of nitrogen especially from automobile exhaust
Examples of smog in a Sentence
the city's smog was once so bad that darkness often prevailed, even at noon
Recent Examples on the Web
Hawaii volcano erupts again spewing toxic gases and volcanic smog
Mini dachshund puppy hosts first birthday sleepover, internet can't cope
Newsweek has contacted aimeecutie for comment via Reddit.
—
John Yoo and John Shu, Newsweek, 24 Jan. 2025
In subsequent comments, Cal Fire said no emissions or smog inspections were conducted and warned that a vehicle failure in a fire zone could be fatal.
—Stephen Hobbs, Sacramento Bee, 17 Jan. 2025
There were no emissions or smog tests performed on the vehicles, according to a Jan. 11 Facebook post by Cal Fire.
—Joedy McCreary, USA TODAY, 14 Jan. 2025
The greenhouse gas rating is a 5 and the smog rating is a 6; both out of 10.
—Tony Leopardo, The Mercury News, 12 Jan. 2025
See all Example Sentences for smog 
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
John Yoo and John Shu, Newsweek, 24 Jan. 2025
In subsequent comments, Cal Fire said no emissions or smog inspections were conducted and warned that a vehicle failure in a fire zone could be fatal.
—Stephen Hobbs, Sacramento Bee, 17 Jan. 2025
There were no emissions or smog tests performed on the vehicles, according to a Jan. 11 Facebook post by Cal Fire.
—Joedy McCreary, USA TODAY, 14 Jan. 2025
The greenhouse gas rating is a 5 and the smog rating is a 6; both out of 10.
—Tony Leopardo, The Mercury News, 12 Jan. 2025
See all Example Sentences for smog
Dictionary Entries Near smog
Cite this Entry
“Smog.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/smog. Accessed 30 Jan. 2025.
Copy CitationKids Definition
smog
noun
ˈsmäg 
also ˈsmȯg
: a thick haze caused by the action of sunlight on air polluted especially by smoke and automobile exhaust fumes
Etymology
from smoke and fog
Love words? Need even more definitions?
Merriam-Webster unabridged
Share