pervicacious

from The Collaborative International Dictionary of English v.0.48

Pervicacious \Per`vi*ca"cious\, a. [L. pervicax, -acis.]
   Obstinate; willful; refractory. [Obs.] --
   {Per`vi*ca"cious*ly}, adv. -- {Per`vi*ca"cious*ness}, n.
   [Obs.]
   [1913 Webster]