radioisotope

noun

ra·​dio·​iso·​tope ˌrā-dē-ō-ˈī-sə-ˌtōp How to pronounce radioisotope (audio)
: a radioactive isotope
radioisotopic
ˌrā-dē-ō-ˌī-sə-ˈtä-pik How to pronounce radioisotope (audio)
-ˈtō-
adjective
radioisotopically
ˌrā-dē-ō-ˌī-sə-ˈtä-pi-k(ə-)lē How to pronounce radioisotope (audio)
adverb

Examples of radioisotope 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.
Solar power and radioisotopes are seen as the shorter-term power solution on the moon with nuclear microreactors considered the permanent fix. — Jordan Blum, Fortune, 25 Oct. 2026 Fuel cycle ambitions grow The deal also marks a shift for Radnostix, which plans to concentrate on radioisotope technologies used in medical and industrial applications after the sale. — Neetika Walter, Interesting Engineering, 1 Oct. 2026 Some of these radioisotopes enter the solar system to fall on all the planets and moons, including Earth and its moon. — Keith Cooper, Space.com, 2 Sep. 2026 For example, unlike plutonium, which has been used in nuclear batteries deployed in Mars rovers and deep space probes, tritium is considered a relatively low-risk radioisotope. — Tereza Pultarova, IEEE Spectrum, 10 Aug. 2026 See All Example Sentences for radioisotope

Word History

Etymology

International Scientific Vocabulary

First Known Use

1938, in the meaning defined above

Time Traveler
The first known use of radioisotope was in 1938

Rhymes for radioisotope

See All Rhymes for radioisotope

Browse Nearby Words

radioimmunoassay
radioisotope
radioisotopic
See all Nearby Words

Cite this Entry

“Radioisotope.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioisotope. Accessed 28 Oct. 2026.

Copy Citation

Kids Definition

radioisotope

noun
ra·​dio·​iso·​tope ˌrād-ē-ō-ˈī-sə-ˌtōp How to pronounce radioisotope (audio)
: a radioactive isotope

Medical Definition

More from Merriam-Webster on radioisotope

Britannica.com: Encyclopedia article about radioisotope

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Last Updated: - Updated example sentences

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of grotesque

See Definitions and Examples »

Popular in Grammar & Usage

See More

How to Use 'Who' vs. 'Whom'

Merriam-Webster’s Great Big List of Words You Love to Hate

'Affect' vs. 'Effect'

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Why is '-ed' sometimes pronounced at the end of a word?
See More

Popular in Wordplay

See More

The Longest Long Words List

9 Words That Sound Like Insults But Aren't

12 Lovely and Unusual Words for the Natural World

Why do we 'bury the lede?'

'Za' and 9 Other Words to Help You Win at SCRABBLE
See More

Popular

See More

How to Use 'Who' vs. 'Whom'

The Longest Long Words List

9 Words That Sound Like Insults But Aren't
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
different halloween monsters in silhouette
A Monstrous Vocab Quiz Words That Go Bump in the Night
See All