soberness vs sober

soberness is a noun but sober is not a noun.

Word	Noun	Adjective	Verb	Adverb
soberness	Yes	No	No	No
sober	No	Yes	Yes	No

soberness (noun)	sober (noun)
a manner that is serious and solemn
the state of being sober and not intoxicated by alcohol

soberness (adjective)	sober (adjective)
	not affected by a chemical substance (especially alcohol)
	completely lacking in playfulness
	lacking brightness or color; dull
	dignified and somber in manner or character and committed to keeping promises

soberness (verb)	sober (verb)
	become sober after excessive alcohol consumption
	become more realistic
	cause to become sober