verb (used without object), crum·bled, crum·bling.
2. to fall into small pieces; break or part into small fragments.
3. to decay or disintegrate gradually:
The ancient walls had crumbled.
4. a crumbly or crumbled substance.
5. crumbles,bits of crisp bacon, bread, etc., added to other foods, especially as a topping.
The ceiling began to crumble. Be careful not to burn the crumble topping. Without trust, the structure will eventually crumble. Keep the cookie size small when spooning or shaping the cookies so they will not fall apart or crumble.