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
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
Cite this Entry
“Radioactive.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radioactive. Accessed 26 Aug. 2026.
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