trigger vs hair trigger

trigger and hair trigger both are nouns.

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

As nouns, hair trigger is a hyponym of trigger; that is, hair trigger is a word with a more specific, narrower meaning than trigger:

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

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