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
Adding more radioactivity to the Alaskan ecosystem would likely result in higher rates of cancer.
—
Shoshi Parks, Popular Science, 14 Aug. 2025
Local governments filed suit against the company after the Detroit Free Press broke the story locally in August 2024 that the landfill was preparing to take 6,000 cubic yards of soil and concrete with elevated radioactivity from the Niagara Falls Storage Site in Lewiston, New York.
—Keith Matheny, Freep.com, 8 Aug. 2025
Outside experts have been quick to point out critical information missing from the DOE's nest report, including the absolute level of radioactivity found in the nest, the specific isotopes that were found, and the type of wasps that built the nest.
—Beth Mole, ArsTechnica, 4 Aug. 2025
Post office fallout shelters were issued standard kits for measuring radioactivity after a nuclear attack.
—IEEE Spectrum, 1 Aug. 2025
See All Example Sentences for radioactivity
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Shoshi Parks, Popular Science, 14 Aug. 2025
Local governments filed suit against the company after the Detroit Free Press broke the story locally in August 2024 that the landfill was preparing to take 6,000 cubic yards of soil and concrete with elevated radioactivity from the Niagara Falls Storage Site in Lewiston, New York.
—Keith Matheny, Freep.com, 8 Aug. 2025
Outside experts have been quick to point out critical information missing from the DOE's nest report, including the absolute level of radioactivity found in the nest, the specific isotopes that were found, and the type of wasps that built the nest.
—Beth Mole, ArsTechnica, 4 Aug. 2025
Post office fallout shelters were issued standard kits for measuring radioactivity after a nuclear attack.
—IEEE Spectrum, 1 Aug. 2025
See All Example Sentences for radioactivity
Cite this Entry
“Radioactivity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactivity. Accessed 10 Sep. 2025.
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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