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Synonyms

smog

American  
[smog, smawg] / smɒg, smɔg /

noun

  1. smoke or other atmospheric pollutants combined with fog in an unhealthy or irritating mixture.

  2. photochemical smog.

verb (used with object)

  1. to cover or envelop with or as if with smog.

smog British  
/ smɒɡ /

noun

  1. a mixture of smoke, fog, and chemical fumes

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
smog Scientific  
/ smŏg /

  1. A form of air pollution produced by the reaction of sunlight with hydrocarbons, nitrogen compounds, and other gases primarily released in automobile exhaust. Smog is common in large urban areas, especially during hot, sunny weather, where it appears as a brownish haze that can irritate the eyes and lungs. Ozone, a toxic gas that is not normally produced at lower atmospheric levels, is one of the primary pollutants created in this kind of smog.

  2. Also called photochemical smog

  3. Fog that has become polluted with smoke and particulates, especially from burning coal.

smog Cultural  

  1. A haze or fog composed of water vapor, complex molecules, and suspended particles.

Discover More

In North America, the primary cause of smog is pollution from automobile exhaust.

The Los Angeles basin, where pollutants can be trapped by inversions and the surrounding mountains, has frequent problems with smog, as do other major urban areas.

The word smog is a combination of smoke and fog.

Other Word Forms

  • desmog verb (used with object)
  • smoggy adjective
  • smogless adjective

Etymology

Origin of smog

1900–05; sm(oke) + ( f)og 1

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

“Today we can say all aboard on what will be the highest ridership light rail in the country, easier commutes, less smog, more access to housing.”

From Los Angeles Times • Mar. 26, 2026

Smoglandia is a four-part series on L.A.’s historic battle with smog.

From Los Angeles Times • Mar. 26, 2026

In truth, ever since we’ve built towns and cities, we’ve made smog — whatever you call it.

From Los Angeles Times • Mar. 26, 2026

The Altadena schoolgirl was witnessing the Big Bang of L.A. smog.

From Los Angeles Times • Mar. 26, 2026

An hour later they were sitting on the beach and staring out at the wall of smog across the horizon.

From "The Road" by Cormac McCarthy

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.