/ Dictionary / Index A aftertreatment: Meaning and Definition of Find definitions for: af•ter•treat•ment Pronunciation: (af'tur-trēt"munt, äf'-), [key] — n. a chemical treatment to which a fabric is subjected immediately after being dyed, for increasing the fastness of the color. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. aftertime afterward Related Content Daily Word Quiz: rotund Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language