: 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
In contrast, the new measurements, which were gathered at a different wavelength of 12.8 micrometers, suggest not only a thick, carbon dioxide-rich atmosphere but one that includes highly reflective haze, akin to smog seen here on Earth.
—
Sharmila Kuthunur, Space.com, 18 Dec. 2024
Neighborhoods where most of the population is Black or Latino tend to be disproportionately hit by heat and smog due to a lack of green spaces or proximity to highways, studies have found.
—Kristal Dixon, Axios, 25 Nov. 2024
Air quality in Northern India has deteriorated over the past week, with toxic smog obscuring India's famed monument to love, the Taj Mahal, about 220 km (136 miles) from New Delhi, as well as Sikhism's holiest shrine, the Golden Temple in Amritsar.
—Fox News, 14 Nov. 2024
Experts say India’s air pollution is so bad that smog could take years off the lives of hundreds of millions of people.
—Sophia Saifi, CNN, 4 Nov. 2024
See all Example Sentences for smog 
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Sharmila Kuthunur, Space.com, 18 Dec. 2024
Neighborhoods where most of the population is Black or Latino tend to be disproportionately hit by heat and smog due to a lack of green spaces or proximity to highways, studies have found.
—Kristal Dixon, Axios, 25 Nov. 2024
Air quality in Northern India has deteriorated over the past week, with toxic smog obscuring India's famed monument to love, the Taj Mahal, about 220 km (136 miles) from New Delhi, as well as Sikhism's holiest shrine, the Golden Temple in Amritsar.
—Fox News, 14 Nov. 2024
Experts say India’s air pollution is so bad that smog could take years off the lives of hundreds of millions of people.
—Sophia Saifi, CNN, 4 Nov. 2024
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 8 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
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