excitation vs unexciting

excitation is a noun but unexciting is not a noun.

Word	Noun	Adjective	Verb	Adverb
excitation	Yes	No	No	No
unexciting	No	Yes	No	No

excitation (noun)	unexciting (noun)
something that agitates and arouses
the neural or electrical arousal of an organ or muscle or gland
the state of being emotionally aroused and worked up

excitation (adjective)	unexciting (adjective)
	not exciting
	not stimulating