#1 crumble v. [crumple, tumble, break down, collapse] fall apart; "the building crumbled after the explosion"; "Negotiations broke down". wn
#2 crumble v. [fall apart] break or fall apart into fragments; "The cookies crumbled"; "The Sphinx is crumbling". wn
#3 crumble v. [decay, dilapidate] fall into decay or ruin; "The unoccupied house started to decay". wn
vizzz