I.firm, determined; esp. in a bad sense, stubborn, obstinate, headstrong, wilful (not in Cic. or Cæs.): tu pertinaciam esse, Antiloche, hanc praedicas: Ego pervicaciam aio et eā me uti volo ... Nam pervicacem dici me esse et vincere Perfacile patior: pertinacem nil moror? Att. ap. Non. 432, 32 sq. (Trag. Rel. v. 8 Rib.); cf.: “adversus peritos pervicax,” Tac. H. 1, 26; Ter. Hec. 4, 1, 17: “musa,” Hor. C. 3, 3, 70: “accusatio,” Tac. A. 13, 33; 3, 33: “pervicacissimi Latinorum,” Flor. 1, 11, 11: “pervicacioris irae fuit,” Curt. 8, 6, 1: “homines pervicaci audaciā, pertinaci spe,” App. de Deo Socr. p. 43 fin.—
B. Of things, steady, unmoved: “contra flatus pervicax libra,” Plin. 16, 36, 65, § 161.—
II. Transf., in a good sense, steadfast, firm: “recti pervicax, constans adversus metus,” Tac. H. 4, 5.—Hence, adv.: pervĭ-cācĭter , stoutly, stiffly, stubbornly, obstinately: “pervicaciter perstare,” Dig. 26, 10, 3. —Comp.: “pervicacius causam belli quaerere,” Liv. 42, 14; Tac. A. 4, 42; 13, 54 fin.