persistency vs pertinacity

persistency and pertinacity both are nouns.

Word	Noun	Adjective	Verb	Adverb
persistency	Yes	No	No	No
pertinacity	Yes	No	No	No

As nouns, persistency and pertinacity are synonyms defined as:

Other synonyms of persistency include doggedness, perseverance, persistence, tenaciousness, tenacity.

persistency (noun)	pertinacity (noun)
persistent determination	persistent determination