elusiveness vs elusive

elusiveness is a noun but elusive is not a noun.

Word	Noun	Adjective	Verb	Adverb
elusiveness	Yes	No	No	No
elusive	No	Yes	No	No

elusiveness (noun)	elusive (noun)
the quality of being difficult to grasp or pin down

elusiveness (adjective)	elusive (adjective)
	skillful at eluding capture
	making great mental demands; hard to comprehend or solve or believe
	difficult to detect or grasp by the mind or analyze
	difficult to describe