[per.ti.na.cious] adj [L pertinac-, pertinax, fr. per- thoroughly + tenac-, tenax tenacious, fr. tenere] (1626) 1 a: adhering resolutely to an opinion, purpose, or design b: perversely persistent
2: stubbornly unyielding or tenacious syn see obstinate -- per.ti.na.cious.ly adv -- per.ti.na.cious.ness n -- per.ti.nac.i.ty n