1. the symbol or banner of a left-wing revolutionary party.
2. a danger signal.
3. something that provokes an angry or hostile reaction: The talk about raising taxes was a red flag to many voters.
4. Also called powder flag . Naut. a red burgee, designating in the International Code of Signals the letter "B," flown by itself to show that a vessel is carrying, loading, or discharging explosives or highly inflammable material.
5. ( caps. ) a war game the U.S. Air Force holds several times each year at Nellis Air Force Base, Nevada, to train personnel in air combat.
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