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]