converging vs convergency

converging and convergency both are nouns.

Word	Noun	Adjective	Verb	Adverb
converging	Yes	No	No	No
convergency	Yes	No	No	No

As nouns, converging and convergency are synonyms defined as:

Other synonyms of converging include convergence.

converging (noun)	convergency (noun)
the act of converging (coming closer)	the act of converging (coming closer)
	the approach of an infinite series to a finite limit