crumble in WordNet English dictionary

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