red flag

1. A flag that serves as a warning signal (synset 107280324)
   "we didn't swim at the beach because the red flag was up"
   is a type of:

   • alarm, alarum, alert, warning signal - an automatic signal (usually a sound) warning of danger
   • flag, signal flag - a rectangular piece of fabric used as a signalling device
2. The emblem of socialist revolution (synset 106895294)
   is a type of: allegory, emblem - a visible symbol representing an abstract idea
3. Something that irritates or demands immediate action (synset 100426618)
   "doing that is like waving a red flag in front of a bull"
   is a type of: annoyance, annoying, irritation, vexation - the act of troubling or annoying someone

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