irritant vs bother

irritant and bother both are nouns.

Word	Noun	Adjective	Verb	Adverb
irritant	Yes	No	No	No
bother	Yes	No	Yes	No

As nouns, bother is a hypernym of irritant; that is, bother is a word with a broader meaning than irritant:

Other hypernyms of irritant include annoyance, botheration, infliction, nuisance, pain, pain in the ass, pain in the neck.

irritant (noun)	bother (noun)
something that causes irritation and annoyance	something or someone that causes trouble; a source of unhappiness
	an angry disturbance

irritant (verb)	bother (verb)
	cause annoyance in; disturb, especially by minor irritations
	make confused or perplexed or puzzled
	make nervous or agitated
	intrude or enter uninvited
	take the trouble to do something; concern oneself
	to cause inconvenience or discomfort to