: a heavy radioactive gaseous element formed by the decay of radium see Chemical Elements Table
Examples of radon in a Sentence
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The biochemist is leading an interdisciplinary team of scientists at the University of Calgary that is looking at the environmental causes of lung cancer, including exposure to radon.
—
Laura Baisas, Popular Science, 9 Oct. 2025
Or just smarter smoke alarms and radon detectors that also check for dozens of different contaminants.
—John Koetsier, Forbes.com, 8 Sep. 2025
And who has the responsibility to get rid of the radon?
—Jill Terreri Ramos, New York Times, 26 Apr. 2025
First, there is no building in the United States without some radon.
—Nick Rosenberger, Idaho Statesman, 22 Apr. 2025
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Laura Baisas, Popular Science, 9 Oct. 2025
Or just smarter smoke alarms and radon detectors that also check for dozens of different contaminants.
—John Koetsier, Forbes.com, 8 Sep. 2025
And who has the responsibility to get rid of the radon?
—Jill Terreri Ramos, New York Times, 26 Apr. 2025
First, there is no building in the United States without some radon.
—Nick Rosenberger, Idaho Statesman, 22 Apr. 2025
See All Example Sentences for radon
Cite this Entry
“Radon.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radon. Accessed 19 Oct. 2025.
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Medical Definition
radon
noun
ra·don
ˈrā-dän 
: a heavy radioactive gaseous element of the group of inert gases formed by disintegration of radium and used similarly to radium in medicine
—symbol Rn
called also radium emanation
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