spontaneous vs spontaneousness

spontaneous is not a noun while spontaneousness is a noun.

Word	Noun	Adjective	Verb	Adverb
spontaneous	No	Yes	No	No
spontaneousness	Yes	No	No	No

spontaneous (noun)	spontaneousness (noun)
	the quality of being spontaneous and coming from natural feelings without constraint

spontaneous (adjective)	spontaneousness (adjective)
happening or arising without apparent external cause
said or done without having been planned or written in advance