1. the hard outer layer of bread
2. the solid outer layer of the earth
Usage: geology
3. a hard layer that forms on the surface of something

1. to form a hard outer layer

Examples

• She cut the crust off her sandwich.
• The earth’s crust is made of solid rock.
• A thin crust of ice formed on the pond overnight.
• The pie had a golden, flaky crust.
• Salt will crust on the surface when the water evaporates.
• He prefers bread with a thick, chewy crust.
• Scientists study the movement of the earth’s crust.