radioactivity
noun
ra·dio·ac·tiv·i·ty
ˌrā-dē-ō-ak-ˈti-və-tē 
: the property possessed by some elements (such as uranium) or isotopes (such as carbon 14) of spontaneously emitting energetic particles (such as electrons or alpha particles) by the disintegration of their atomic nuclei
also
: the rays emitted
Examples of radioactivity in a Sentence
Recent Examples on the Web
The International Atomic Energy Agency, World Health Organization, and Food and Agriculture Organization all have programs that look for radioactivity in foods to keep unsafe food off the market.
—
Eduardo B. Farfán, The Conversation, 21 Apr. 2026
Damage to the facility’s outer protective structure has compromised safety functions designed to prevent the release of radioactivity into the environment.
—Aman Tripathi, Interesting Engineering, 15 Apr. 2026
Then, that soil will be tested for radioactivity, wrapped in special packaging and stored in heavy-metal containers.
—Andy Sheehan, CBS News, 14 Apr. 2026
Alatáriel Marie There have been many famous Maries through history, but perhaps the most heroic of them all was Marie Curie, a Polish-French physicist and chemist, who conducted groundbreaking, Nobel Prize winning research on radioactivity.
—Taylor Grothe, Parents, 10 Apr. 2026
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Eduardo B. Farfán, The Conversation, 21 Apr. 2026
Damage to the facility’s outer protective structure has compromised safety functions designed to prevent the release of radioactivity into the environment.
—Aman Tripathi, Interesting Engineering, 15 Apr. 2026
Then, that soil will be tested for radioactivity, wrapped in special packaging and stored in heavy-metal containers.
—Andy Sheehan, CBS News, 14 Apr. 2026
Alatáriel Marie There have been many famous Maries through history, but perhaps the most heroic of them all was Marie Curie, a Polish-French physicist and chemist, who conducted groundbreaking, Nobel Prize winning research on radioactivity.
—Taylor Grothe, Parents, 10 Apr. 2026
See All Example Sentences for radioactivity
Cite this Entry
“Radioactivity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactivity. Accessed 29 Apr. 2026.
Copy CitationKids Definition
radioactivity
noun
ra·dio·ac·tiv·i·ty
-ˌak-ˈtiv-ət-ē
: the giving off of rays of energy or particles by the breaking apart of atoms of certain elements (as uranium)
Medical Definition
radioactivity
noun
ra·dio·ac·tiv·i·ty
-ak-ˈtiv-ət-ē
plural radioactivities
: the property possessed by some elements (as uranium) or isotopes (as carbon 14) of spontaneously emitting energetic particles (as electrons or alpha particles) by the disintegration of their atomic nuclei
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