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

Drones deployed in New Jersey to search for missing radioactive material Our rating: False No drones were used in the search for the substance, according to a spokesperson for the New Jersey agency in charge of overseeing its recovery. —Andre Byik, USA TODAY, 23 Dec. 2024

Officials push back on online rumors, say mystery drones are not tracking radioactive material Is the hysteria over drones warranted? —Tom Hanson, CBS News, 22 Dec. 2024

Some have suggested that the drones are secretly sniffing out radioactive materials, while others have questioned whether their origins are from another foreign power. —Avery Lotz, Axios, 19 Dec. 2024

The Missouri Republican, who just won reelection, was disappointed Johnson did not include language and funding to expand the Radiation Exposure Compensation Act to cover people in the St. Louis area affected by radioactive materials left over from the World War II-era Manhattan Project. —Alexander Bolton, The Hill, 19 Dec. 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