/ ˌpɜːtɪˈneɪʃəs; NAmE ˌpɜːrtnˈeɪ-/ adjective
( formal ) determined to achieve a particular aim despite difficulties or opposition
► per·tin·acity / ˌpɜːtɪˈnæsəti; NAmE ˌpɜːrtnˈæ-/ noun [ U ]
••
WORD ORIGIN
early 17th cent.: from Latin pertinax , pertinac- holding fast + -ous .