|1.||a. the hard outer part of bread|
|b. a piece of bread consisting mainly of this|
|2.||the baked shell of a pie, tart, etc|
|3.||any hard or stiff outer covering or surface: a crust of ice|
|4.||sial See also sima the solid outer shell of the earth, with an average thickness of 30--35 km in continental regions and 5 km beneath the oceans, forming the upper part of the lithosphere and lying immediately above the mantle, from which it is separated by the Mohorovičić discontinuity|
|5.||the dry covering of a skin sore or lesion; scab|
|6.||a layer of acid potassium tartrate deposited by some wine, esp port, on the inside of the bottle|
|7.||the hard outer layer of such organisms as lichens and crustaceans|
|9.||slang (Brit), (Austral), (NZ) a living (esp in the phrase earn a crust)|
|10.||to cover with or acquire a crust|
|11.||to form or be formed into a crust|
|[C14: from Latin crūsta hard surface, rind, shell]|
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.
|crust (krŭst) Pronunciation Key
The solid, outermost layer of the Earth, lying above the mantle. ◇ The crust that includes continents is called continental crust and is about 35.4 to 70 km (22 to 43.4 mi) thick. It consists mostly of rocks, such as granites and granodiorites, that are rich in silica and aluminum, with minor amounts of iron, magnesium, calcium, sodium, and potassium. ◇ The crust that includes ocean floors is called oceanic crust and is about 4.8 to 9.7 km (3 to 6 mi) thick. It has a similar composition to that of continental crust, but has higher concentrations of iron, magnesium, and calcium and is denser than continental crust. The predominant type of rock in oceanic crust is basalt.
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.