/ Dictionary / Index R retroact: Meaning and Definition of Find definitions for: ret•ro•act Pronunciation: (re'trō-akt"), [key] — v.i. to act in opposition; react. to have reference to or influence on past occurrences. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. retro retroaction Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language