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]