sober vs playfulness

sober is not a noun while playfulness is a noun.

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

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

sober (adjective)	playfulness (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

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