Crumbly describes something that breaks apart easily into small pieces or crumbs. A cookie fresh from the oven might be perfectly crumbly, breaking into delicious fragments with the gentlest pressure. Old cheese, dried-out cake, or certain types of soil can all be crumbly, falling apart when you handle them.

When something is crumbly, it wants to become crumbs. Sometimes this is exactly what you want: a crumbly pie crust or crisp bacon that crumbles when you bite it. Other times it's frustrating: trying to slice a crumbly block of feta cheese can leave you with a pile of fragments instead of neat pieces.

Texture matters here. Crumbly things have a particular structure that makes them break cleanly into bits rather than squish, stretch, or shatter. Fresh bread is soft but stays together. Glass is hard but shatters into sharp pieces. But that perfectly aged cheddar cheese? Beautifully crumbly, breaking into satisfying fragments.