Word forms: red flags
Definitions1. countable noun
A red flag is a flag that is red in colour and is used as a symbol to represent communism and socialism or to indicate danger or as a sign that you should stop. ⇒ They waved red flags and shouted, 'Lenin, yes'. ⇒ Then the rain came and the red flag went up to signal a halt.2. countable noun If you refer to something as a red flag, you mean that it acts as a danger signal. ⇒ The abnormal bleeding is your body's own red flag of danger.
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