/ Dictionary / Index A act of war: Meaning and Definition of Find definitions for: act' of war' Pronunciation: [key] an act of aggression by a country against another with which it is nominally at peace. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Act of Uniformity actomyosin Related Content Daily Word Quiz: nefarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language