1) Determination 2) Doggedness 3) French word used in English 4) Perseverance 5) Persistence 6) Persistency 7) Persistent determination 8) Purpose 9) Tenaciousness 10) Tenacity Found on https://www.crosswordclues.com/clue/pertinacity
Per`ti·nac'i·ty noun [ Confer French pertinacité .] The quality or state of being pertinacious; obstinacy; perseverance; persistency. Macaulay. Syn. -- See Obstinacy . Found on http://www.encyclo.co.uk/webster/P/63