red flag
1 Americannoun
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the symbol or banner of a left-wing revolutionary party.
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a danger signal.
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something that provokes an angry or hostile reaction.
The talk about raising taxes was a red flag to many voters.
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Also called powder flag. Nautical. 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.
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(initial capital letters) 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.
verb (used with object)
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to mark or draw attention to for a particular purpose.
The department has red-flagged the most urgent repair work to be done.
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to provoke the attention of; alert; arouse.
The animal's refusal to eat red-flagged the keeper that something was wrong.
adjective
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of or relating to a red flag.
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intended or serving to emphasize, warn, incite, or provoke.
noun
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a symbol of socialism, communism, or revolution
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a warning of danger or a signal to stop
noun
Etymology
Origin of red flag1
First recorded in 1770–80
Origin of red-flag2
First recorded in 1880–85
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Proposition 40’s failure to crack 50% support among voters at this point in the electoral cycle is a potential red flag, said IGS poll director Mark DiCamillo.
From Los Angeles Times ● Aug. 14, 2026
Companies that don’t would raise a red flag, leaving investors wondering what they have against keeping the market fully informed throughout the year.
From The Wall Street Journal ● Jul. 26, 2026
It was a red flag day with triple-digit temperatures and a strong, dry wind blowing from the south.
From Los Angeles Times ● Jul. 25, 2026
Is the surge in initial public offerings a red flag for investors?
From MarketWatch ● Jul. 23, 2026
Whenever Stanton had a baby, a flag was raised outside her house—a red flag for a boy, white for a girl.
From "Votes for Women!" by Winifred Conkling
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“We have a red-flag system here, where if there’s anything that gets really out of whack, they can immediately tag the milk, and it doesn’t go to anything but cheese,” McAfee told me.
From Salon ● Jun. 22, 2026
You are in big red-flag territory for this one.
From MarketWatch ● May 26, 2026
Yamaji wasn’t involved in the deliberations on issuing the alert, but said he believed that the decision to red-flag the stock was appropriate.
From The Wall Street Journal ● Dec. 4, 2025
The first person to crash was Williams' Alex Albon, who hit the inside apex at Turn One, causing the first of three red-flag stoppages in the first session.
From BBC ● Sep. 20, 2025
She denounced it as a “hodgepodge of plagiarism pulled from here, a bit from there, the whole misinterpreted and sensationalized to give color to the red-flag word SPIES.”
From "The Woman All Spies Fear" by Amy Butler Greenfield
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In recent years, the Air Force has looked for new ways to use the Reaper in combat, sending it to large-scale combat exercises, including Valiant Shield in the Pacific and Red Flag in Alaska.
From The Wall Street Journal ● Mar. 16, 2026
Although the winds are trending weaker, esp. for vlys & coasts, Red Flag Warnings have been extended through Thur 8PM.
From Los Angeles Times ● Jan. 21, 2025
He then got into his Chinese Hongqi, or "Red Flag," limousine and departed the airport into the city, where demonstrations are expected both for and against his visit.
From Reuters ● Nov. 14, 2023
There are nearly 38,000 companies in critical financial distress, according to data prepared by analysts Red Flag for Begbies Traynor.
From BBC ● Oct. 30, 2023
Our escorts deigned us an occasional glance, but they had a soft job; we were not gnashing our teeth or singing the "Marseillaise" or "The Red Flag."
From Nights in London by Thomas Burke
The race was twice red-flagged after incidents before eventually being won by Fabio di Giannantonio in Barcelona.
From BBC ● May 17, 2026
For instance, a corporate group of high-handicap golfers who haven’t played the course before can be red-flagged in advance.
From The Wall Street Journal ● Apr. 10, 2026
Mercedes duo Kimi Antonelli and George Russell completed the podium in a sprint that was red-flagged after Piastri and Alpine's Franco Colapinto' exited the 100km dash.
From Barron's ● Nov. 8, 2025
The National Trust said Portstewart Strand had been red-flagged and advised visitors against going into the water.
From BBC ● Aug. 4, 2025
“Again I swung my red-flagged brassey in front of the angry creature’s face, and what I had hoped for followed.”
From Mr. Munchausen Being a True Account of Some of the Recent Adventures beyond the Styx of the Late Hieronymus Carl Friedrich, Sometime Baron Munchausen of Bodenwerder by John Kendrick Bangs
“Passing judgments, applying labels, and red-flagging educational materials that might prompt uncomfortable but insightful discussions are activities that do not belong in our public schools.”
From Washington Post ● Nov. 10, 2019
From next season players will be tested every day for six minutes before training, with computers immediately red-flagging anyone at risk.
From The Guardian ● Apr. 7, 2013
But we make the caddie do the ordinary work of carrying, and teeing up, and red-flagging also, and he contrives in effect to be in two places at the same time.
From The Happy Golfer Being Some Experiences, Reflections, and a Few Deductions of a Wandering Golfer by Henry Leach
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.