errancy vs errant

errancy is a noun but errant is not a noun.

Word	Noun	Adjective	Verb	Adverb
errancy	Yes	No	No	No
errant	No	Yes	No	No

errancy (noun)	errant (noun)
fallibility as indicated by erring or a tendency to err
(Christianity) holding views that disagree with accepted doctrine; especially disagreement with papal infallibility

errancy (adjective)	errant (adjective)
	straying from the right course or from accepted standards
	uncontrolled motion that is irregular or unpredictable