Main Entry: ra·dio·ac·tiv·i·ty

Pronunciation: \-ak-ˈtiv-ət-ē\

Function: noun

Inflected Form(s): plural ra·dio·ac·tiv·i·ties

: the property possessed by some elements (as uranium) or isotopes (as carbon 14) of spontaneously emitting energetic particles (as electrons or alpha particles) by the disintegration of their atomic nuclei