arousal vs irritation

arousal and irritation both are nouns.

Word	Noun	Adjective	Verb	Adverb
arousal	Yes	No	No	No
irritation	Yes	No	No	No

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

arousal (noun)	irritation (noun)
the act of arousing	unfriendly behavior that causes anger or resentment
mutual sexual fondling prior to sexual intercourse	the act of troubling or annoying someone
awakening from sleep	an uncomfortable feeling of mental painfulness or distress
a state of heightened physiological activity	a sudden outburst of anger
	the psychological state of being irritated or annoyed
	the neural or electrical arousal of an organ or muscle or gland
	(pathology) abnormal sensitivity to stimulation