Synonyms of red flag

Noun

1. red flag, flag, signal flag, alarm, alert, warning signal, alarum

usage: a flag that serves as a warning signal; "we didn't swim at the beach because the red flag was up"

2. red flag, emblem, allegory

usage: the emblem of socialist revolution

3. red flag, annoyance, annoying, irritation, vexation

usage: something that irritates or demands immediate action; "doing that is like waving a red flag in front of a bull"