pertinacity vs persistency

pertinacity and persistency both are nouns.

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

As nouns, pertinacity and persistency are synonyms defined as:

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

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