radioactivity
noun
- nuclear decay process
- measure of emission of ionizing radiation by a substance
Wiktionary
Pronunciation: /ˌreɪdɪəʊakˈtɪvɪti/
noun
Etymology: From radioactive + -ity or radio- + activity.
- Spontaneous emission of ionizing radiation as a consequence of a nuclear reaction, or directly from the breakdown of an unstable nucleus.
“Today, no one would intentionally smear radioactive materials on their face, but in 1933, the dangers of radioactivity were not yet fully understood.”
- The radiation so emitted; including gamma rays, alpha particles, neutrons, electrons, positrons, etc.