The Collaborative International Dictionary of English v.0.48:

Perseverance \Per`se*ver"ance\ (p[~e]r`s[-e]*v[=e]r"ans), n. [F.
   pers['e]v['e]rance, L. perseverantia.]
   1. The act of persevering; persistence in anything
      undertaken; continued pursuit or prosecution of any
      business, or enterprise begun. "The king-becoming graces .
      . . perseverance, mercy, lowliness." --Shak.
      [1913 Webster]

            Whose constant perseverance overcame
            Whate'er his cruel malice could invent. --Milton.
      [1913 Webster]

   2. Discrimination. [Obs.] --Sir J. Harrington.
      [1913 Webster]

   3. (Theol.) Continuance in a state of grace until it is
      succeeded by a state of glory; sometimes called final
      perseverance, and the perseverance of the saints. See
      Calvinism.
      [1913 Webster]

   Syn: Persistence; steadfastness; constancy; steadiness;
        pertinacity.
        [1913 Webster]

WordNet (r) 3.0 (2006):

perseverance
    n 1: persistent determination [syn: doggedness,
         perseverance, persistence, persistency, tenacity,
         tenaciousness, pertinacity]
    2: the act of persisting or persevering; continuing or repeating
       behavior; "his perseveration continued to the point where it
       was no longer appropriate" [syn: perseverance,
       persistence, perseveration]

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "perseverance":
   acceptance, assiduity, balkiness, bigotry, bullheadedness,
   commitment, continualness, continuance, continuation, continuity,
   decidedness, decision, decisiveness, dedication, definiteness,
   determinateness, determination, determinedness, devotion,
   diligence, doggedness, dogmatism, earnestness, endurance,
   extension, fanaticism, firmness, fixed mind, forbearance,
   forbearing, forbearingness, fortitude, grit, guts, hardheadedness,
   headstrongness, indefatigability, indulgence, inflexibility,
   inflexible will, intolerance, lengthening, lenience, leniency,
   long-sufferance, long-suffering, longanimity, maintenance,
   mulishness, obduracy, obdurateness, obstinacy, obstinateness,
   opinionatedness, overzealousness, patience, patience of Job,
   patientness, perpetuation, persistence, pertinacity, pigheadedness,
   pluck, progress, progression, prolongation, protraction, purpose,
   purposefulness, pursuance, relentlessness, repetition,
   resoluteness, resolution, resolve, resolvedness, restiveness, run,
   sedulousness, self-control, self-will, seriousness, sincerity,
   single-mindedness, stamina, staying power, steadfastness,
   stiff neck, stiff-neckedness, stoicism, straight course,
   strongheadness, stubbornness, sufferance, sulkiness, sullenness,
   sustained action, sustenance, sweet reasonableness, tenaciousness,
   tenacity, tirelessness, tolerance, toleration, total commitment,
   uncooperativeness, uninterrupted course, unregenerateness,
   unremittingness, waiting game, waiting it out, way, will,
   willfulness



The Devil's Dictionary (1881-1906):

PERSEVERANCE, n.  A lowly virtue whereby mediocrity achieves an
inglorious success.

    "Persevere, persevere!" cry the homilists all,
    Themselves, day and night, persevering to bawl.
    "Remember the fable of tortoise and hare --
    The one at the goal while the other is -- where?"
    Why, back there in Dreamland, renewing his lease
    Of life, all his muscles preserving the peace,
    The goal and the rival forgotten alike,
    And the long fatigue of the needless hike.
    His spirit a-squat in the grass and the dew
    Of the dogless Land beyond the Stew,
    He sleeps, like a saint in a holy place,
    A winner of all that is good in a race.
                                                          Sukker Uffro