• The spontaneous disintegration of unstable atomic nuclei, such as those of uranium or curium, mainly through the emission of alpha, beta, or gamma rays. Also called decay (2).
  • A specific instance of radioactivity (1), such as that occurring when an atom of uranium-238 emits an alpha particle to form an atom of thorium-234. Also called decay (3).
  • The reduction over time of the radioactivity of a substance, due to radioactivity (1). Also called decay (4).
  • synonym radioactive decay
  • synonym radioactive disintegration
  • noun a gradual disintegration of the nucleus of radioactive matter

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