red flag vs vexation

red flag and vexation both are nouns.

Word	Noun	Adjective	Verb	Adverb
red flag	Yes	No	No	No
vexation	Yes	No	No	No

As nouns, vexation is a hypernym of red flag; that is, vexation is a word with a broader meaning than red flag:

Other hypernyms of red flag include annoyance, annoying, irritation.

red flag (noun)	vexation (noun)
something that irritates or demands immediate action	the act of troubling or annoying someone
a flag that serves as a warning signal	something or someone that causes anxiety; a source of unhappiness
the emblem of socialist revolution	anger produced by some annoying irritation
	the psychological state of being irritated or annoyed