inconsistent vs inconsistency

inconsistent is not a noun while inconsistency is a noun.

Word	Noun	Adjective	Verb	Adverb
inconsistent	No	Yes	No	No
inconsistency	Yes	No	No	No

inconsistent (noun)	inconsistency (noun)
	the quality of being inconsistent and lacking a harmonious uniformity among things or parts
	the relation between propositions that cannot both be true at the same time

inconsistent (adjective)	inconsistency (adjective)
displaying a lack of consistency
not in agreement
not capable of being made consistent or harmonious