Definition of crust

The word "crust" has its roots in Old English. The term originally referred to the outer, hard layer of the earth's surface, as well as the outer covering of fruit, like a walnut shell. This sense of the word has been preserved in modern usage, as in "crust of the earth" or "crust of a fruit." In Middle English (circa 1100-1500), the term began to be used to describe the outer layer of a baked good, like bread or pastry. From there, the meaning expanded to include other types of cooked foods, like the crust on a pie. The word "crust" is ultimately derived from the Old English word "crust" or "cryst", which is related to the Latin word "crusta", meaning "shell" or "covering". Today, the word "crust" is used in various contexts, including geology, food, and even English idiom (e.g., "living on the crust" meaning to barely make a living).