radioactive

adjective

ra·​dio·​ac·​tive ˌrā-dē-ō-ˈak-tiv How to pronounce radioactive (audio)
1
: of, caused by, or exhibiting radioactivity
radioactive isotopes
Radon is an odorless, colorless gas that arises naturally from the ground because of the decay of radioactive elements commonly found in rocks and many types of soil. In a chain of radioactive decay, uranium produces radium, which gives off radon, which in turn produces radioactive breakdown products that are harmful if inhaled.Warren E. Leary
2
: so divisive or controversial as to require avoidance
He has been deemed radioactive by most charitable organizations … and organized competition, even local stuff, is largely closed off to him.Asher Price
Almost all women—and therefore men—use a form of birth control at some point in their lives, yet contraception is so politically and legally radioactive that legislators and pharmaceutical companies avoid funding it.Karen Weise
Subsequent polling data show that the quota issue is perhaps the most powerful one in our politics … A House Democratic aide says, "The quota issue is radioactive." The result has been nothing less than panic in the Democratic ranks.Elizabeth Drew
radioactively adverb
Plutonium is the only one of these transuranic elements that can exist a fair amount of time before radioactively decaying into lighter elements. James Kaler

Examples of radioactive in a Sentence

Uranium and plutonium are radioactive.
Recent Examples on the Web By the definition that an earlier panel of experts spent nearly a decade and a half debating and crafting, the Anthropocene started in the mid-20th century, when nuclear bomb tests scattered radioactive fallout across our world. Raymond Zhong, New York Times, 5 Mar. 2024 In 2012, the Navajo Nation Council passed the Radioactive and Related Substances Equipment, Vehicles, Persons, and Materials Transportation Act, expressing opposition to hauling radioactive products across Navajo Nation lands. Trilce Estrada Olvera, The Arizona Republic, 5 Mar. 2024 The Department of Energy notes that the amount of nuclear waste produced by power plants each year would fill half an Olympic sized swimming pool, while low-level radioactive waste, such as from hospitals, is twenty five times that. Michael Lynch, Forbes, 1 Mar. 2024 With Kanye helming the production and serving as the lead artist, Ty colored between the lines and kept the songs rock steady despite Ye’s radioactive raps. Carl Lamarre, Billboard, 27 Feb. 2024 The military also spread radioactive sand across a simulated American town to track the movement of contamination and conducted radiation experiments on sheep and cows to appalling effect. John Metcalfe, The Mercury News, 26 Feb. 2024 Opponents also note the long-term issue of radioactive waste storage, and in some cases assert that nuclear can stall the growth of renewables such as wind and solar. Tribune News Service, Orange County Register, 25 Feb. 2024 In another accidental leak in October, four workers were sprayed with radioactive liquid waste while cleaning a treatment facility. Mari Yamaguchi, Quartz, 21 Feb. 2024 But officials said two new radioactive objects were recently found at the site, which is reportedly earmarked for the city’s biggest development project. Melissa Chan, NBC News, 27 Jan. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'radioactive.' 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

1898, in the meaning defined at sense 1

Time Traveler
The first known use of radioactive was in 1898

Dictionary Entries Near radioactive

Cite this Entry

“Radioactive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactive. Accessed 19 Mar. 2024.

Kids Definition

radioactive

adjective
ra·​dio·​ac·​tive ˌrād-ē-ō-ˈak-tiv How to pronounce radioactive (audio)
: of, caused by, or exhibiting radioactivity
radioactively adverb

Medical Definition

radioactive

adjective
ra·​dio·​ac·​tive ˌrād-ē-ō-ˈak-tiv How to pronounce radioactive (audio)
: of, caused by, or exhibiting radioactivity
radioactive isotopes
radioactively adverb

More from Merriam-Webster on radioactive

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