adjacency vs adjacent

adjacency is a noun but adjacent is not a noun.

Word	Noun	Adjective	Verb	Adverb
adjacency	Yes	No	No	No
adjacent	No	Yes	No	No

adjacency (noun)	adjacent (noun)
the attribute of being so near as to be touching

adjacency (adjective)	adjacent (adjective)
	nearest in space or position; immediately adjoining without intervening space
	having a common boundary or edge; abutting; touching
	near or close to but not necessarily touching