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

Examples of radioactive in a Sentence

Uranium and plutonium are radioactive.

Recent Examples on the Web

Meanwhile, nearby residents have been living in fear of a potential radioactive disaster. —Robyn Dixon, Washington Post, 8 Apr. 2024

Some miles down is the West Lake landfill, a pit holding thousands of tons of radioactive waste that originated at Mallinckrodt and was illegally dumped in an area now surrounded by chain restaurants, warehouses, and a hospital. —Catie Edmondson, New York Times, 6 Apr. 2024

Some of my favorite keepers are from glass made with radioactive uranium, which glows under black light. —Angela Andaloro, Peoplemag, 4 Apr. 2024

By 2010, a growing underground fire about 1,000 feet from the radioactive material was discovered. —Catie Edmondson, New York Times, 6 Apr. 2024

An accident involving military equipment and ordnance could damage the systems needed to cool the reactors, and could lead to a leak of radioactive material. —Nataliya Gumenyuk, The Atlantic, 6 Mar. 2024

None of these fragments, ESA said, contain toxic or radioactive substances. —John Tufts, The Indianapolis Star, 23 Feb. 2024

Clues pointing to the radioactive waste emerged in the process of sorting through this DDT history. —Rosanna Xia, Los Angeles Times, 21 Feb. 2024

Godzilla: Final Wars (2004) Godzilla: Final Wars was conceived as a 50th birthday bash for everyone’s favorite radioactive threat turned fearsome protector of mankind. —Katie Rife, EW.com, 28 Mar. 2024

Word History

Etymology

International Scientific Vocabulary

First Known Use

1898, in the meaning defined at sense 1

Kids 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