The Collaborative International Dictionary of English v.0.48:

Friable \Fri"a*ble\, a. [L. friabilis, fr. friare to rub, break,
   or crumble into small pieces, cf. fricare to rub, E. fray:
   cf. F. friable.]
   Easily crumbled, pulverized, or reduced to powder. "Friable
   ground." --Evelyn. "Soft and friable texture." --Paley. --
   Fri'a*ble*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

friable
    adj 1: easily broken into small fragments or reduced to powder;
           "friable sandstone"; "friable carcinomatous tissue";
           "friable curds formed in the stomach";"crumbly cookies"
           [syn: crumbly, friable]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "friable":
   breakable, brittle, brittle as glass, crackable, crimp, crisp,
   crispy, crumbly, crump, crushable, delicate, fissile, flimsy,
   fracturable, fragile, frail, frangible, lacerable, pulverizable,
   pulverulent, scissile, shatterable, shattery, shivery, splintery,
   triturable, vulnerable