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.
Schools should monitor radon levels regularly and fix any high levels with mitigation systems. — Rebecca Smullin Dawson, The Conversation, 25 Sep. 2026 Overall Winner World Food Photography Awards The Khoja Obi Garm sanatorium (health hotel) is a colossal concrete complex built on radon-rich hot springs in the mountains of Tajikistan. — Cecilia Rodriguez, Forbes.com, 18 June 2026 Order a low-cost radon test kit from the American Lung Association. — Ryan Brennan, Kansas City Star, 19 May 2026 Low-cost radon test kits are available through the American Lung Association or by calling 1-800-SOS-RADON. — Ryan Brennan may 19, Charlotte Observer, 19 May 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 9 Oct. 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

Britannica.com: Encyclopedia article about radon

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