clumsiness vs clumsy

clumsiness is a noun but clumsy is not a noun.

Word	Noun	Adjective	Verb	Adverb
clumsiness	Yes	No	No	No
clumsy	No	Yes	No	No

clumsiness (noun)	clumsy (noun)
the carriage of someone whose movements and posture are ungainly or inelegant
the inelegance of someone stiff and unrelaxed (as by embarrassment)
unskillfulness resulting from a lack of training

clumsiness (adjective)	clumsy (adjective)
	lacking grace in movement or posture
	not elegant or graceful in expression
	showing lack of skill or aptitude
	difficult to handle or manage especially because of shape