The Collaborative International Dictionary of English v.0.48:

Pertinacity \Per`ti*nac"i*ty\, n. [Cf. F. pertinacit['e].]
   The quality or state of being pertinacious; obstinacy;
   perseverance; persistency. --Macaulay.
   [1913 Webster]

   Syn: See Obstinacy.
        [1913 Webster]

WordNet (r) 3.0 (2006):

pertinacity
    n 1: persistent determination [syn: doggedness,
         perseverance, persistence, persistency, tenacity,
         tenaciousness, pertinacity]

Moby Thesaurus II by Grady Ward, 1.0:

95 Moby Thesaurus words for "pertinacity":
   application, assiduity, assiduousness, balkiness, bigotry,
   bulldog courage, bulldog tenacity, bullheadedness, concentration,
   constancy, demandingness, determination, diligence,
   dogged perseverance, doggedness, dogmatism, endurance, engrossment,
   exigency, fanaticism, fidelity, fixed mind, fortitude, gameness,
   gaminess, grittiness, hardheadedness, hardihood, hardiness,
   headstrongness, importunacy, importunateness, importunity,
   indefatigability, industriousness, industry, inflexible will,
   insistence, insistency, intolerance, loyalty, mettlesomeness,
   mulishness, nerviness, obduracy, obstinacy, obstinateness,
   opinionatedness, overzealousness, patience, patience of Job,
   permanence, perseverance, persistence, persistency,
   pertinaciousness, pigheadedness, plodding, pluckiness, plugging,
   preoccupation, pressingness, pressure, relentlessness,
   resoluteness, resolution, restiveness, sedulity, sedulousness,
   self-will, single-mindedness, singleness of purpose, slogging,
   spunkiness, stability, stamina, staying power, steadfastness,
   steadiness, stick-to-itiveness, stiff neck, stiff-neckedness,
   strongheadness, stubbornness, sulkiness, sullenness, tenaciousness,
   tenacity, tirelessness, uncooperativeness, unregenerateness,
   unremittingness, unswerving attention, urgency, willfulness