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

Example Sentences

Recent Examples on the Web Worldwide, the consensus is that deep underground disposal is the best way to keep nuclear waste away from water sources and the food chain until its radioactivity has decayed to the normal background.

Howard Lee, Ars Technica, 17 Aug. 2022 The capital again is preparing for the release of radioactivity, with more than 1,000 personnel trained to respond, said Roman Tkachuk, head of the capital’s Municipal Security Department.

Adam Schreck, BostonGlobe.com, 4 Nov. 2022 This type of uranium, which hasn’t been enriched like the type used for nuclear weapons, has a fraction of the amount of radioactivity, according to the International Atomic Energy Agency.

Caroline Eubanks, Washington Post, 11 Oct. 2022 There’s a plaque marking the site and the U.S. Department of Energy still keeps tabs on low-level radioactivity under the ground.

Chicago Tribune, 24 Aug. 2022 Noyes said that the waste water will be filtered before any discharge and that any remaining radioactivity would be well below the levels deemed safe by the NRC.

Mike Damiano, BostonGlobe.com, 26 July 2022 Scientists continue working to decommission and decontaminate the plant, which still has more than 1.24 million tonnes of water contaminated with radioactivity on site.

Sophie Mellor, Fortune, 14 July 2022 Another other notable anomaly is in the mass of the W-boson, a subatomic particle involved in the action of the weak nuclear force that governs some types of radioactivity.

Tom Metcalfe, NBC News, 14 June 2022 The announcement -- the first-ever official disclosure of a nuclear accident by the Soviet Union -- came hours after the Scandinavian countries reported abnormally high levels of radioactivity in their skies.

San Diego Union-Tribune, 26 Apr. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'radioactivity.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

Etymology

International Scientific Vocabulary

First Known Use

1899, in the meaning defined above

Time Traveler

The first known use of radioactivity was in 1899

See more words from the same year

Dictionary Entries Near radioactivity

radioactive series

radioactivity

radioallergosorbent

See More Nearby Entries

Cite this Entry

Style

“Radioactivity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactivity. Accessed 7 Dec. 2022.

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Kids 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