radon

noun

ra·​don ˈrā-ˌdän 

: 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

Houvouras suspects she was exposed to radon in her childhood home in Greenville, South Carolina, which the EPA has designated as having the highest potential for elevated indoor radon levels. —Adrianna Rodriguez, USA Today, 10 Nov. 2025

While countries like the UK offer radon risk maps, Dallas warns against relying on assumptions. —Christopher McFadden, Interesting Engineering, 24 Oct. 2025

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

Word History

Etymology

International Scientific Vocabulary, from radium

First Known Use

1918, in the meaning defined above

Rhymes for radon

• anton
• argon
• axon
• baronne
• baryon
• baton
• boron
• buisson
• bygone
• capon
• cardon
• chiffon

Kids Definition

radon

noun

ra·​don ˈrā-ˌdän 

: a heavy radioactive gaseous element formed by the breaking apart of radium atoms see element

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

see Chemical Elements Table