endlessness vs endless

endlessness is a noun but endless is not a noun.

Word	Noun	Adjective	Verb	Adverb
endlessness	Yes	No	No	No
endless	No	Yes	No	No

endlessness (noun)	endless (noun)
the property of being (or seeming to be) without end

endlessness (adjective)	endless (adjective)
	having the ends united so as to form a continuous whole
	having no known beginning and presumably no end
	tiresomely long; seemingly without end
	infinitely great in number