Radioactive means giving off energy as its atoms break down. Radioactive waste, a radioactive isotope, highly radioactive.
The rate is fixed and unstoppable, which is what makes half-lives so useful for dating things and so awkward for waste. The Curies coined the word in 1898. Bananas are faintly radioactive, from the potassium in them, which is a useful sense of scale.
1adjectiveradioactiveGiving off energy as its atoms break down.
“Workers wear special suits when they handle radioactive waste.”
radioactive is a property of matter.
Coined by Pierre and Marie Curie in French in 1898, from radio-, ray, plus active.
French
radioactif
English, today
radioactive
Borrowed from French radioactif. Coined by Pierre Curie and Marie Curie in 1898 as French radioactif, equivalent to English radio + active.
Etymology from Wiktionary, CC BY-SA