Crumbliness describes how readily a product breaks into small fragments when handled or bitten, a texture term for brittleness and fragility. It is prized in shortbread, aged cheeses, and dry cakes, where it signals the intended delicate structure, but counts as a defect in foods meant to slice cleanly. Food scientists link it to low moisture, weak protein networks, and fat-shortened matrices, measuring fracture behaviour and tuning formulation and baking to hit the target. Sensory panels score crumbliness alongside hardness and fracturability when profiling biscuit and cheese textures.