Other forms: crumbling, crumbled, crumbles
A crumble is baked fruit under a rough sweet topping. Apple or rhubarb below, flour and butter rubbed to crumbs above.
It is a British pudding of the war years, invented when pastry needed too much fat and sugar, and it has comfortably outlived the shortage. It is served hot with custard, which is not optional in most households. The verb is where the name comes from, since to crumble is to break into small pieces, and buildings, empires and resolve can all crumble.
Crumble is crumb with the ending that means to keep doing it. Old English crymel was a little crumb, so crumbling is making crumbs over and over again.
Old English
*crymlan — to crumble
Middle English
*crymblen
English, today
crumble
Built from
From earlier crymble, crimble, from Middle English crymblen, kremelen, from Old English crymlan (“to crumble”), from crymel (“a small crumb; crumble”), diminutive of Old English cruma (“crumb”), equivalent to crumb + le. Compare Dutch kruimelen (“to crumble”), German Low German krömmeln (“to crumble”), German Krümel, diminutive of German Krume, German krümeln, krümmeln (“to crumble”). Alteration of vowel due to analogy with crumb.
Etymology from Wiktionary, CC BY-SA