Crusty describes something with a hard, crispy outer layer. Fresh bread often has a crusty exterior that crunches when you bite into it, while the inside stays soft and fluffy. Pizza, pies, and rolls can all be crusty. That golden-brown surface forms when heat drives moisture out of the dough, leaving behind a satisfying crunch.

The word also describes things that have dried and hardened on the surface. Old paint becomes crusty and flakes off. Mud that splattered on your shoes dries into a crusty coating. Snow that melts slightly and refreezes turns crusty instead of powdery.

People sometimes use crusty to describe someone who seems grumpy, impatient, or rough around the edges. A crusty sea captain might bark orders and complain about everything, but still have a softer side underneath that tough exterior. Like crusty bread, a crusty person has a hard outer layer that might hide something warmer inside.