adjective
radioactive
ray-dee-oh-AKTIHV
adjective
1
Giving off radiation from the decay of unstable atomic nuclei.
"Radioactive waste must be stored safely for thousands of years."
2
Figuratively, so controversial or toxic that people avoid it.
"After the scandal, his name became politically radioactive."
How to Use Radioactive
Learner’s notesIn plain EnglishEmitting radiation from unstable atoms, or figuratively, too toxic or controversial to touch.
Common pairings
radioactive material
radioactive decay
politically radioactive
Word Forms
more radioactive comparative, radioactives plural, most radioactive superlative
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_____ waste must be stored safely for thousands of years.
Etymology
Coined by Pierre and Marie Curie in 1898 as the French radio-actif, from "radio-" plus "active".