irritate vs hassle

irritate is not a noun while hassle is a noun.

Word	Noun	Adjective	Verb	Adverb
irritate	No	No	Yes	No
hassle	Yes	No	Yes	No

As verbs, hassle is a hyponym of irritate; that is, hassle is a word with a more specific, narrower meaning than irritate:

irritate (noun)	hassle (noun)
	disorderly fighting
	an angry disturbance

irritate (verb)	hassle (verb)
excite to an abnormal condition, or chafe or inflame	annoy continually or chronically
excite to some characteristic action or condition, such as motion, contraction, or nervous impulse, by the application of a stimulus
cause annoyance in; disturb, especially by minor irritations