The Collaborative International Dictionary of English v.0.48:

Endurance \En*dur"ance\, n. [Cf. OF. endurance. See Endure.]
   1. A state or quality of lasting or duration; lastingness;
      continuance.
      [1913 Webster]

            Slurring with an evasive answer the question
            concerning the endurance of his own possession.
                                                  --Sir W.
                                                  Scott.
      [1913 Webster]

   2. The act of bearing or suffering; a continuing under pain
      or distress without resistance, or without being overcome;
      sufferance; patience.
      [1913 Webster]

            Their fortitude was most admirable in their patience
            and endurance of all evils, of pain and of death.
                                                  --Sir W.
                                                  Temple.

   Syn: Suffering; patience; fortitude; resignation.
        [1913 Webster]

WordNet (r) 3.0 (2006):

endurance
    n 1: the power to withstand hardship or stress; "the marathon
         tests a runner's endurance"
    2: a state of surviving; remaining alive [syn: survival,
       endurance]

Moby Thesaurus II by Grady Ward, 1.0:

157 Moby Thesaurus words for "endurance":
   abidingness, acceptance, age, antiquity, application, assiduity,
   assiduousness, bulldog tenacity, changelessness, concentration,
   constancy, continualness, continuance, continuation, continuity,
   decisiveness, defeat of time, defiance of time, diligence,
   diuturnity, dogged perseverance, doggedness, durability,
   durableness, duration, energy, engrossment, extension, fidelity,
   firmness, fixedness, forbearance, forbearing, forbearingness,
   force, fortitude, frozenness, guts, gutsiness, hardening,
   hardiness, heartiness, immobility, immovability, immovableness,
   immutability, indefatigability, indulgence, industriousness,
   industry, insistence, insistency, intestinal fortitude,
   invariability, invariableness, inveteracy, lastingness,
   lengthening, lenience, leniency, lifetime, long standing,
   long-lastingness, long-livedness, long-sufferance, long-suffering,
   longanimity, longevity, loyalty, lustihood, lustiness, maintenance,
   might, mightiness, obstinacy, patience, patience of Job,
   patientness, perdurability, perennation, permanence, permanency,
   perpetualness, perpetuation, perpetuity, perseverance, persistence,
   persistency, pertinaciousness, pertinacity, plodding, plugging,
   potency, power, powerfulness, preoccupation, progress, progression,
   prolongation, protraction, pursuance, quiescence, relentlessness,
   repetition, resolution, rigidity, robustness, ruggedness, run,
   sedulity, sedulousness, self-control, single-mindedness,
   singleness of purpose, slogging, solidity, stability, stalwartness,
   stamina, standing, stasis, staying power, steadfastness,
   steadiness, stick-to-itiveness, sticking power, stoicism,
   stoutness, straight course, strength, strength of will,
   stubbornness, sturdiness, sufferance, survival, survivance,
   sustained action, sustenance, sweet reasonableness, tenaciousness,
   tenacity, tirelessness, tolerance, toleration, torpor, toughness,
   unchangeability, unchangingness, uninterrupted course,
   unremittingness, unswerving attention, vigor, vigorousness,
   vitality, waiting game, waiting it out, way