/ Dictionary / Index R radioactive waste: Meaning and Definition of Find definitions for: ra'dioac'tive waste' Pronunciation: [key] the radioactive by-products from the operation of a nuclear reactor or from the reprocessing of depleted nuclear fuel. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. radioactive series radioactivity Related Content Daily Word Quiz: mamba Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language