playfulness vs sober

playfulness is a noun but sober is not a noun.

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

playfulness (noun)	sober (noun)
activities that are enjoyable or amusing
a disposition to find (or make) causes for amusement
a festive merry feeling

playfulness (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

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