The Collaborative International Dictionary of English v.0.48:

Durability \Du`ra*bil"i*ty\, n. [L. durabilitas.]
   The state or quality of being durable; the power of
   uninterrupted or long continuance in any condition; the power
   of resisting agents or influences which tend to cause
   changes, decay, or dissolution; lastingness.
   [1913 Webster]

         A Gothic cathedral raises ideas of grandeur in our
         minds by the size, its height, . . . its antiquity, and
         its durability.                          --Blair.
   [1913 Webster]

WordNet (r) 3.0 (2006):

durability
    n 1: permanence by virtue of the power to resist stress or
         force; "they advertised the durability of their products"
         [syn: lastingness, durability, enduringness,
         strength]

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "durability":
   abidingness, body, ceaselessness, changelessness, coeternity,
   cohesiveness, concreteness, constancy, continualness, continuance,
   density, durableness, duration, endlessness, endurance,
   eternalness, eternity, ever-duringness, everlastingness, everness,
   firmness, fixedness, foreverness, frozenness, hardening, hardiness,
   hardness, immobility, immovability, immovableness, immutability,
   incessancy, indestructibility, infinite duration, infinity,
   infrangibility, interminability, invariability, invariableness,
   inveteracy, lastingness, leatherlikeness, long standing, mass,
   materiality, never-endingness, palpability, perdurability,
   perenniality, perennialness, permanence, permanency, perpetualness,
   perpetuity, persistence, persistency, ponderability, quiescence,
   resistance, rigidity, ropiness, sempiternity, solidity, soundness,
   stability, stamina, standing, stasis, steadfastness, steadiness,
   stiffness, stoutness, strength, stringiness, stubbornness,
   sturdiness, substance, substantiality, substantialness,
   tangibility, tenacity, timelessness, torpor, toughness,
   unbreakability, unbreakableness, unceasingness, unchangeability,
   unchangingness, viscidity, vitality