hair trigger vs trigger

hair trigger and trigger both are nouns.

Word	Noun	Adjective	Verb	Adverb
hair trigger	Yes	No	No	No
trigger	Yes	No	Yes	No

As nouns, trigger is a hypernym of hair trigger; that is, trigger is a word with a broader meaning than hair trigger:

Other hypernyms of hair trigger include gun trigger.

hair trigger (noun)	trigger (noun)
a gun trigger that responds with little pressure	an act that sets in motion some course of events
	lever that activates the firing mechanism of a gun
	a device that activates or releases or causes something to happen

hair trigger (verb)	trigger (verb)
	release or pull the trigger on
	put in motion or move to act