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Meaning of radioactivity

ra•di•o•ac•tiv•i•ty

Pronunciation: (rā"dē-ō-ak-tiv'i-tē), [key]
— n. Physics, Chem.
  1. the phenomenon, exhibited by and being a property of certain elements, of spontaneously emitting radiation resulting from changes in the nuclei of atoms of the element. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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