smog

noun

ˈsmäg How to pronounce smog (audio)
ˈsmȯg
: 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
smogless
ˈsmä-gləs How to pronounce smog (audio)
ˈsmȯ-
adjective

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
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.
Grove’s proposal, Senate Bill 712 — dubbed Leno’s Law — would exempt vehicles 35 years or older from California’s smog check program. Hector Amezcua, Sacbee.com, 9 Apr. 2025 More than any other eastern state, Connecticut has suffered from this due to prevailing wind currents dumping pollution, greenhouse gases and summertime smog here that emanate from midwestern and upwind power plants and other industrial sources. Jan Ellen Spiegel, Hartford Courant, 28 Mar. 2025 Cities that were once notorious for their thick, choking smog – such as Los Angeles, Houston and Pittsburgh – now see far cleaner air, while lakes and forests devastated by acid rain in the Northeast have rebounded. Richard E. Peltier, The Conversation, 12 Mar. 2025 The gas can form volcanic smog (vog) when exposed to the atmosphere, and long-term exposure to vog can cause irritation of the eyes, throat and lungs. David Faris, Newsweek, 18 Jan. 2025 See All Example Sentences for smog

Word History

Etymology

smoke + fog

First Known Use

1880, in the meaning defined above

Time Traveler
The first known use of smog was in 1880

Browse Nearby Words

Cite this Entry

“Smog.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/smog. Accessed 24 Apr. 2025.

Kids Definition

smog

noun
ˈsmäg How to pronounce smog (audio)
 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

Medical Definition

smog

noun
ˈsmäg also ˈsmȯg
: 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

More from Merriam-Webster on smog

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!