a red flag as the symbol of socialist revolution or a warning of danger: figurativethey had overlooked the red flags that should have alerted them to the county’s disastrous investment strategy
(the Red Flag) the anthem of Britain’s Labour Party, a socialist song with words written in 1889 by James Connell (1852–1929) and sung to the tune of the German song ‘O Tannenbaum’.
red flag in other Oxford dictionaries
Definition of red flag in the US English dictionary
