Source : Webster's Revised Unabridged Dictionary (1913)

Crumble \Crum"ble\ (kr?m"b'l), v. t. [imp. & p. p. {Crumbled}
   (-b'ld); p. pr. & vb. n. {Crumbling} (-bl?ng).] [Dim. of
   crumb, v. t., akin to D. krimelen G. kr?meln.]
   To break into small pieces; to cause to fall in pieces.

         He with his bare wand can unthread thy joints, And
         crumble all thy sinews.                  --Milton.

Crumble \Crum"ble\, v. i.
   To fall into small pieces; to break or part into small
   fragments; hence, to fall to decay or ruin; to become
   disintegrated; to perish.

         If the stone is brittle, it will crumble and pass into
         the form of gravel.                      --Arbuthnot.

         The league deprived of its principal supports must soon
         crumble to pieces.                       --Prescott.

Source : WordNet®

crumble
     v 1: fall apart; "the building crimbled after the explosion";
          "Negociations broke down" [syn: {crumple}, {tumble}, {break
          down}, {collapse}]
     2: break or fall apart into fragments; "The cookies crumbled";
        "The Sphinx is crumbling" [syn: {fall apart}]
     3: fall into decay or ruin; "The unoccupied house started to
        decay" [syn: {decay}, {delapidate}]