To crumble is to break into small pieces, or to fall to pieces.
(verb)See crumble in Webster's New World College Dictionary
See crumble in American Heritage Dictionary 4
crum·ble
verb crumbled crum·bled, crumbling crum·bling, crum·bles verb, transitiveOrigin: Alteration (influenced by crumb) of Middle English cremelen, from Old English *crymelen, frequentative of gecrymmian, to break into crumbs, from cruma, crumb.
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