Английский разговорный словарь (основной) - pertinacious
Pertinacious
pertinacious
ˌpə:tɪˈneɪʃəs adj. stubborn; persistent; obstinate (in a course of action etc.). øøpertinaciously adv. pertinaciousness n. pertinacity n. [L pertinax (as PER-, tenax tenacious)]