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.
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 Testing heat without sunlight Zeno’s payload centers on a five-watt radioisotope heater unit containing americium-241. — Aamir Khollam, Interesting Engineering, 20 Aug. 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 Both Voyager probes run on radioisotope thermoelectric generators, or devices that convert the heat provided by decaying plutonium into electricity. — Ashley Strickland, CNN Money, 6 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 6 Sep. 2026.

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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

Last Updated: - Updated example sentences
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