Source : Webster's Revised Unabridged Dictionary (1913)

Pertinacy \Per"ti*na*cy\, n. [L. pertinere to pertain. See
   {Pertinence}.]
   The quality or state of being pertinent; pertinence. [Obs.]

Pertinacy \Per"ti*na*cy\, n. [L. pertinacia, fr. pertinax. See
   {Pertinacious}.]
   Pertinacity. [Obs.] --Chaucer.