- a sign of a particular issue requiring attention.
- a warning of danger.
- a sign of danger.
- a clue that a problem is present.
- labeling something as a warning.
- United, American, and Delta airlines suspended all flights to China. This was a red flag as the coronavirus wreaked havoc on the airline industry.
- This is the third time that Handy has attempted to raise a red flag.
- I consider the decision a red flag for every democratic-minded citizen.
- This, to my mind, is a danger signal and a huge red flag.
The expression “raise a red flag” originates from different usages of real flags throughout history. The armed forces frequently fly red flags as a warning to the public that live exercises are happening. At times, ships carrying munitions fly a red flag. In many nations, people fly a red flag to signify that there is an outdoor shooting range in use. A red flag placed on the beach warns of hazardous water conditions. Red flags of different designs indicate dangerous wave and wind conditions for mariners. In automotive racing, red flags symbolize that a race has ended. In the 1600s, armies used a red flag to signal that they were ready to go to battle. By the 1700s, the term “red flag” was used as an idiom meaning a warning sign.