/ Dictionary / Index A activated sludge: Meaning and Definition of Find definitions for: ac'tivated sludge' Pronunciation: [key] sludge (def. 8). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. activated mine activation analysis Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language