/ Thesaurus Find synonyms for: Noun1. radiation, radioactivity, emissionusage: the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decayWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.See also: radioactivity (Dictionary) Related Content Daily Word Quiz: apogee Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language Synonyms Index