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:
“How long are these kids talking to chatbots before there’s a red flag that’s thrown up?”
From The Wall Street Journal ● Sep. 26, 2026
A big red flag for companies: A high credit-utilization score suggests to lenders that you may be a higher risk.
From MarketWatch ● Sep. 22, 2026
Under current rules, the clock does not stop in practice sessions in the event of a red flag caused by an incident, unlike in qualifying and races when the competition is suspended.
From BBC ● Sep. 21, 2026
One person had to wave a red flag while walking in front of the vehicle to warn horses and pedestrians.
From The Wall Street Journal ● Sep. 13, 2026
As for maple leaves, they’re the hardest part to draw on our red flag.
From "Cat's Eye" by Margaret Atwood
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The data only needs to be aggregated; red-flag algorithms need to be programmed in.
From The Wall Street Journal ● Jun. 23, 2026
“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
The elementary school relocates out of town during red-flag days.
From Los Angeles Times ● Nov. 24, 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 Florida, 38 counties are under burn bans and most inland regions in the state are under Red Flag warnings from the weather service.
From The Wall Street Journal ● Apr. 22, 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
“We’re going to act aggressively with any fire during a Red Flag Warning,” Oliveira said.
From Seattle Times ● Nov. 14, 2023
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
And let the White Flag fade To grey; and let the Red Flag fade to pink, For these that climb and climb; and cannot sink So deep as death and honour, Déroulède.
From Poems by G. K. (Gilbert Keith) Chesterton
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
In August, BBC News NI reported that some patients who have been red-flagged for breast cancer assessments are waiting up to 10 weeks to be seen.
From BBC ● Nov. 18, 2025
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
We got out and away from the grand old town just as the park of artillery opened fire from their great guns on their red-flagged targets far out to sea.
From The Cruise of the Land-Yacht "Wanderer" Thirteen Hundred Miles in my Caravan by Gordon Stables
“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.