radon
/ˈɹeɪdɒn/noun
radon is a noun meaning “The chemical element (symbol Rn, formerly Ro) with atomic number 86. It is an odorless, colorless, chemically inert but radioactive noble gas” (English Wiktionary, September 2026). It is spelled R-A-D-O-N and has 2 syllables, and it appears about once in every 1 million words in written English (wordfreq, 2021 data).
What does radon mean?
noun
- 1
The chemical element (symbol Rn, formerly Ro) with atomic number 86. It is an odorless, colorless, chemically inert but radioactive noble gas.
- 2
An atom of this element.
- 3
Radon-222 (22286Rn), the most stable isotope of said element.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
How do you pronounce radon?
- /ˈɹeɪdɒn/
Radon has 2 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Tesco250-radon.wav, LL-Q1860_(eng)-Naomi_Persephone_Amethyst_(NaomiAmethyst)-radon.wav, Wikimedia Commons (author and licence on each file's page).
How common is radon?
Radon appears about once in every 1 million words in written English, the 33,236th most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Radon in Spanish, French, German and Portuguese
In the sense chemical element:
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.