radioactivity

noun

ra·​dio·​ac·​tiv·​i·​ty ˌrā-dē-ō-ak-ˈti-və-tē How to pronounce radioactivity (audio)
: 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 Tests showed 35 employees absorbed elevated levels of radioactivity, though most showed a dose akin to a chest X-ray, the department found. Daniel Moore, Chicago Tribune, 7 May 2023 The radioactivity is limited, so several rounds of treatment are usually needed to tackle the cancer. Calum Chace, Forbes, 21 Apr. 2023 Partners in life and in science, the couple’s fruitful work together produced the discovery of the elements polonium and radium in 1898, as well as radioactivity itself. Stephen C. George, Discover Magazine, 14 Feb. 2023 Other instruments expected to start operating around the same timeframe include a gamma-ray spectrometer for monitoring radioactivity levels and a single-photon stereo camera to measure bioluminescence of deep-sea organisms. Dhananjay Khadilkar, Ars Technica, 31 Mar. 2023 Caesium-137 has a half-life of about 30 years, which means that after three decades, the capsule’s radioactivity would halve, and after 60 years would halve again, meaning the lost capsule could have remained radioactive for as long as 300 years. Hilary Whiteman, CNN, 1 Feb. 2023 While the government estimates relied mostly on data from monitoring stations in Japan, the European research team behind the new report looked at radioactivity data from stations scattered across the globe. Valerie Ross, Discover Magazine, 28 Oct. 2011 Marie Curie was a Polish scientist who discovered both polonium and radium, and coined the term radioactivity. Rebecca Norris, Woman's Day, 27 Jan. 2023 Members of the public can suggest sites that should be tested, collect data on radioactivity, and raise funds to cover the cost of the research. Eva Lewandowski, Discover Magazine, 8 June 2016 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'radioactivity.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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

Dictionary Entries Near radioactivity

Cite this Entry

“Radioactivity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactivity. Accessed 10 Jun. 2023.

Kids Definition

radioactivity

noun
ra·​dio·​ac·​tiv·​i·​ty -ˌak-ˈtiv-ət-ē How to pronounce radioactivity (audio)
: 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 How to pronounce radioactivity (audio)
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

More from Merriam-Webster on radioactivity

Last Updated: - Updated example sentences
Love words? Need even more definitions?

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