Meaning of RADIOACTIVITY in English

RADIOACTIVITY

ˌrādēˌo+ noun

Etymology: International Scientific Vocabulary radio- + activity

: the emission of radiant energy : the property, possessed by some elements (as radium, uranium, thorium, and their products) whether free or combined of spontaneously emitting alpha or beta rays and sometimes also gamma rays by the disintegration of the nuclei of atoms

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.