radon

noun

ra·​don ˈrā-ˌdän How to pronounce radon (audio)
: a heavy radioactive gaseous element formed by the decay of radium see Chemical Elements Table

Examples of radon in a Sentence

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.
Order a low-cost radon test kit from the American Lung Association. — Ryan Brennan, Kansas City Star, 19 May 2026 Long-term tests are more accurate for estimating annual average radon levels. — Jan Lowery, The Conversation, 20 Feb. 2026 That means family history, radon exposure, occupational risk, military exposure. — Armstrong Williams, Baltimore Sun, 1 May 2026 Best air quality monitors This monitor detects radon, carbon dioxide, VOCs, humidity, temperature and atmospheric pressure, giving you a broad understanding of the quality of the air in your home. — Bestreviews, Chicago Tribune, 17 Mar. 2026 See All Example Sentences for radon

Word History

Etymology

International Scientific Vocabulary, from radium

First Known Use

1918, in the meaning defined above

Time Traveler
The first known use of radon was in 1918

Rhymes for radon

See All Rhymes for radon

Browse Nearby Words

radome
radon
radon seed
See all Nearby Words

Cite this Entry

“Radon.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radon. Accessed 7 Jul. 2026.

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Kids Definition

radon

noun
ra·​don ˈrā-ˌdän How to pronounce radon (audio)
: a heavy radioactive gaseous element formed by the breaking apart of radium atoms see element

Medical Definition

radon

noun
ra·​don ˈrā-dän How to pronounce radon (audio)
: 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

see Chemical Elements Table

More from Merriam-Webster on radon

Nglish: Translation of radon for Spanish Speakers

Britannica.com: Encyclopedia article about radon

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