transitive. To break down into crumbs or small fragments, reduce to crumbs. Now rare.

transitive. To break into bits, crumble.

transitive. To crumble, break up.

transitive. To crumble (bread, egg yolks, etc.); to scatter crumbs upon or into (a dish).

transitive. To break down into small crumbs; to reduce to crumbs or small fragments.

transitive. To reduce (a thing) to fragments; to cause to crumble or decay. Also figurative. Also with down.

transitive. To crumble; esp. to crumble (bread) into a bowl in order to soak it in liquid. Also intransitive.

To cause (earth) to crumble. ? dialect.