to break into small fragments or crumbs.

to fall into small pieces; break or part into small fragments.

to decay or disintegrate gradually

The ancient walls had crumbled.

a crumbly or crumbled substance.

crumbles, bits of crisp bacon, bread, etc., added to other foods, esp. as a topping.

British Dialect . crumb; particle; fragment.

verb

build , put together

verb

break up , collapse , crumb , crush , decay , decompose , degenerate , deteriorate , disintegrate , dissolve , fragment , go to pieces , granulate , grind , molder , perish , powder , pulverize , putrefy , triturate , tumble , break down , fragmentize , break , erode , rot , splinter , spoil