red flag

¹ American  

noun

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.  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.

5. (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.

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red-flag ² American  

[red-flag] / ˈrɛdˈflæg /

verb (used with object)

red-flagged, red-flagging

1. to mark or draw attention to for a particular purpose.

   The department has red-flagged the most urgent repair work to be done.

2. to provoke the attention of; alert; arouse.

   The animal's refusal to eat red-flagged the keeper that something was wrong.

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adjective

1. of or relating to a red flag.

2. intended or serving to emphasize, warn, incite, or provoke.

red flag ¹ British  

noun

1. a symbol of socialism, communism, or revolution

2. a warning of danger or a signal to stop

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Red Flag ² British  

noun

1. a socialist song, written by James Connell (1852–1929), Irish political activist, in 1889

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Etymology

Origin of red flag¹

First recorded in 1770–80

Origin of red-flag²

First recorded in 1880–85

Example Sentences

When agencies debate investment bans or export controls, for example, existing designations function as both a red flag encouraging further scrutiny and foundation of evidence upon which other cases can be built.

From Barron's

Waving red flags emblazoned with the yellow and black crest of the KLA, crowds chanted the militia's name as they marched through Pristina's downtown.

From Barron's

Missing multiple events, however, is considered a red flag.

From The Wall Street Journal

If, say, Minnesota is spending significantly more on in-home care services than Wisconsin and Michigan, or is seeing faster growth in those claims, that’s probably a red flag.

From The Wall Street Journal

Although the data don’t amount to an economic red flag yet, the number of mortgages that became overdue by at least 30 days in the fourth quarter increased, as did the number in serious delinquency.

From Barron's