red flag

Meanings

1. A flag that is red, especially associated with leftist revolutionary ideologies.
2. A flag used as a signal that the race must be stopped immediately (and possibly restarted).
3. A cue, warning, or alert; a sign or signal that something is wrong.
4. Something that will enrage a particular person; a red rag.
5. A flag formerly used by a railway guard to warn the driver not to start the train.

1. A series of advanced, realistic air combat training exercises conducted by the U.S. Air Force.
2. A socialist song, emphasising the sacrifices and solidarity of the international labor movement.
3. Synonym of red flag warning