noun🔗ShareSpontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus."The old watch contained radium, which caused its hands to glow in the dark due to radioactivity. "physicsenergysubstancechemistryenvironmentsciencematerialChat with AIVocabulary GamePractice Reading
noun🔗ShareThe radiation so emitted; including gamma rays, alpha particles, neutrons, electrons, positrons, etc."The radioactivity from the old smoke detector is dangerous and should be disposed of properly. "physicsenergysubstancescienceChat with AIVocabulary GamePractice Reading
