radioactive
adjective
ra·dio·ac·tive
ˌrā-dē-ō-ˈak-tiv 
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
Warren E. Leary2
: 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
Asher PriceAlmost 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
Karen WeiseSubsequent 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
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
James Kaler
Examples of radioactive in a Sentence
Uranium and plutonium are radioactive.
Recent Examples on the Web
Four, the largest release of radioactive material in U.S. history occurred in the 1979 Church Rock uranium mine spill not far from Gallup, New Mexico.
—Ian Dexter Palmer, Forbes, 28 Feb. 2025
The charges allege that Pang at one point expected to be paid millions of dollars for his efforts, which would include helping the Iranians smuggle weapons and polonium, a radioactive metal that can be used to covertly poison humans, into the U.S.
—Jason Meisner, Chicago Tribune, 27 Feb. 2025
Certain types of rare earth ores also contain radioactive thorium or uranium, which is often removed using acid.
—Jason Neely and Eric Onstad, USA TODAY, 27 Feb. 2025
The gas forms naturally through many processes, including radioactive decay in the crust.
—Laura Paddison, CNN, 19 Feb. 2025
See All Example Sentences for radioactive
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Ian Dexter Palmer, Forbes, 28 Feb. 2025
The charges allege that Pang at one point expected to be paid millions of dollars for his efforts, which would include helping the Iranians smuggle weapons and polonium, a radioactive metal that can be used to covertly poison humans, into the U.S.
—Jason Meisner, Chicago Tribune, 27 Feb. 2025
Certain types of rare earth ores also contain radioactive thorium or uranium, which is often removed using acid.
—Jason Neely and Eric Onstad, USA TODAY, 27 Feb. 2025
The gas forms naturally through many processes, including radioactive decay in the crust.
—Laura Paddison, CNN, 19 Feb. 2025
See All Example Sentences for radioactive
Articles Related to radioactive
Cite this Entry
“Radioactive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactive. Accessed 13 Mar. 2025.
Copy CitationKids Definition
radioactive
adjective
ra·dio·ac·tive
ˌrād-ē-ō-ˈak-tiv
: of, caused by, or exhibiting radioactivity
radioactively
adverb
Medical Definition
radioactive
adjective
ra·dio·ac·tive
ˌrād-ē-ō-ˈak-tiv
: of, caused by, or exhibiting radioactivity
radioactive isotopes
radioactively
adverb
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