| 1. | the brown, hard outer portion or surface of a loaf or slice of bread (distinguished from crumb ). |
| 2. | a slice of bread from the end of a loaf, consisting chiefly of this. |
| 3. | the pastry covering the outside of a pie or other dish. |
| 4. | a piece of stale bread. |
| 5. | any more or less hard external covering or coating: a crust of snow. |
| 6. | Geology. the outer layer of the earth, about 22 mi. (35 km) deep under the continents and 6 mi. (10 km) deep under the oceans. Compare mantle (def. 3), core 1 (def. 10). |
| 7. | a scab or eschar. |
| 8. | Slang. unabashed self-assertiveness; nerve; gall: He had a lot of crust going to the party without an invitation. |
| 9. | deposit from wine, as it ripens during aging, on the interior of bottles, consisting of tartar and coloring matter. |
| 10. | the hard outer shell or covering of an animal. |
| 11. | Australian Slang. a living or livelihood: What do you do for a crust? |
| 12. | to cover with or as with a crust; encrust. |
| 13. | to form (something) into a crust. |
| 14. | to form or contract a crust. |
| 15. | to form into a crust. |

In geology, the outermost layer of the Earth. It overlies the mantle.
Note: The crust includes the continents and the ocean bottom and is generally estimated to be about five to twenty-five miles thick.
Note: The crust is made from relatively lightweight rocks that floated to the surface when the Earth was molten early in its history.
crust
|
crust (krŭst)
n.
A hard, crisp covering or surface.
An outer layer or coating formed by the drying of a bodily exudate such as pus or blood; a scab.