The Collaborative International Dictionary of English v.0.48:

Durable \Du"ra*ble\, a. [L. durabilis, fr. durare to last: cf.
   F. durable. See Dure.]
   Able to endure or continue in a particular condition;
   lasting; not perishable or changeable; not wearing out or
   decaying soon; enduring; as, durable cloth; durable
   happiness.
   [1913 Webster]

         Riches and honor are with me; yea, durable riches and
         righteousness.                           --Prov. viii.
                                                  18.
   [1913 Webster]

         An interest which from its object and grounds must be
         so durable.                              --De Quincey.

   Syn: Lasting; permanent; enduring; firm; stable; continuing;
        constant; persistent. See Lasting.
        [1913 Webster]

WordNet (r) 3.0 (2006):

durable
    adj 1: existing for a long time; "hopes for a durable peace"; "a
           long-lasting friendship" [syn: durable, lasting,
           long-lasting, long-lived]
    2: capable of withstanding wear and tear and decay; "durable
       denim jeans" [syn: durable, long-wearing]
    3: very long lasting; "less durable rocks were gradually worn
       away to form valleys"; "the perdurable granite of the ancient
       Appalachian spine of the continent" [syn: durable,
       indestructible, perdurable, undestroyable]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "durable":
   abiding, adamantine, age-long, aged, ancient, antique, bulky,
   cartilaginous, changeless, chewy, chronic, cohesive, constant,
   continuing, coriaceous, dense, dependable, diuturnal, enduring,
   evergreen, fast, fibrous, firm, fixed, frozen, gristly, hard,
   hardy, heavy, immobile, immutable, indestructible, intact,
   intransient, inveterate, inviolate, lasting, leatherlike, leathery,
   long-lasting, long-lived, long-standing, long-term, longeval,
   longevous, macrobiotic, massive, of long duration,
   of long standing, perdurable, perduring, perennial, permanent,
   perpetual, persistent, persisting, quiescent, reliable, remaining,
   resistant, rigid, ropy, rugged, sempervirent, sinewy, solid, sound,
   stable, static, stationary, staying, steadfast, steady, stiff,
   stout, stringy, strong, stubborn, sturdy, substantial, sustained,
   tenacious, torpid, tough, tough as leather, unaltered,
   unchangeable, unchanged, unchanging, unchecked, undestroyed,
   unfading, unfailing, unshifting, untiring, unvaried, unvarying,
   unyielding, vigorous, viscid, vital, well-built, well-constructed,
   well-founded, well-grounded, well-made, wiry