incompetent vs incompetency

incompetent and incompetency both are nouns.

Word	Noun	Adjective	Verb	Adverb
incompetent	Yes	Yes	No	No
incompetency	Yes	No	No	No

incompetent (noun)	incompetency (noun)
someone who is not competent to take effective action	lack of physical or intellectual ability or qualifications

incompetent (adjective)	incompetency (adjective)
not qualified or suited for a purpose
legally not qualified or sufficient
not doing a good job
not meeting requirements
showing lack of skill or aptitude