available vs accessibility

available is not a noun while accessibility is a noun.

Word	Noun	Adjective	Verb	Adverb
available	No	Yes	No	No
accessibility	Yes	No	No	No

available (noun)	accessibility (noun)
	the quality of being at hand when needed
	the attribute of being easy to meet or deal with

available (adjective)	accessibility (adjective)
obtainable or accessible and ready for use or service
convenient for use or disposal
not busy; not otherwise committed