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
This included managing massive radioactive waste sites and ensuring the material there doesn't further contaminate nearby communities.
—CBS News, 17 Feb. 2025
This included managing massive radioactive waste sites and ensuring the material there doesn’t further contaminate nearby communities.
—Tara Copp and Anthony Izaguirre, Los Angeles Times, 17 Feb. 2025
This crimson version of the radioactive monster doesn’t appear until late in Brave New World’s final act, suggesting that its inclusion in the marketing was a bit of a desperate move by Marvel.
—David Sims, The Atlantic, 14 Feb. 2025
Unit 4 at Chernobyl – near Ukraine’s border with Belarus – exploded in 1986, sparking a radioactive disaster.
—Daria Tarasova-Markina, CNN, 14 Feb. 2025
See all Example Sentences for radioactive 
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
CBS News, 17 Feb. 2025
This included managing massive radioactive waste sites and ensuring the material there doesn’t further contaminate nearby communities.
—Tara Copp and Anthony Izaguirre, Los Angeles Times, 17 Feb. 2025
This crimson version of the radioactive monster doesn’t appear until late in Brave New World’s final act, suggesting that its inclusion in the marketing was a bit of a desperate move by Marvel.
—David Sims, The Atlantic, 14 Feb. 2025
Unit 4 at Chernobyl – near Ukraine’s border with Belarus – exploded in 1986, sparking a radioactive disaster.
—Daria Tarasova-Markina, CNN, 14 Feb. 2025
See all Example Sentences for radioactive
Articles Related to radioactive
Dictionary Entries Near radioactive
Cite this Entry
“Radioactive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactive. Accessed 20 Feb. 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
Love words? Need even more definitions?
Merriam-Webster unabridged
Share