crust   (krŭst)    n.   The hard outer portion or surface area of bread. A piece of bread consisting mostly of the hard outer portion. A piece of bread that has become hard and dry. The exterior portion of the earth that lies above the Mohorovičić discontinuity. The outermost solid layer of a planet or moon. A pastry shell, as of a pie or tart. A hard crisp covering or surface: snow with a firm crust. A hard deposit formed on the interior of a wine bottle as the wine matures. Geology The exterior portion of the earth that lies above the Mohorovičić discontinuity. The outermost solid layer of a planet or moon. The hard outer covering or integument of certain plants and animals, such as lichens and crustaceans. Pathology An outer layer or coating formed by the drying of a bodily exudate such as pus or blood; a scab. Informal Insolence; audacity; gall. v.   crust·ed, crust·ing, crusts v.   tr. To cover with a crust. To form into a crust. v.   intr. To become covered with a crust. To harden into a crust. [Middle English cruste, from Old French crouste, from Latin crūsta; see kreus- in Indo-European roots.] crust'less adj.

Crust

Crust\ (kr?st), n. [L. crusta: cf. OF. crouste, F. cro[^u]te; prob. akin to Gr. ????? ice, E. crystal, from the same root as E. crude, raw. See Raw, and cf. Custard.]

1. The hard external coat or covering of anything; the hard exterior surface or outer shell; an incrustation; as, a crust of snow.

I have known the statute of an emperor quite hid under a crust of dross. --Addison.

Below this icy crust of conformity, the waters of infidelity lay dark and deep as ever. --Prescott.

2. (Cookery) (a) The hard exterior or surface of bread, in distinction from the soft part or crumb; or a piece of bread grown dry or hard. (b) The cover or case of a pie, in distinction from the soft contents. (c) The dough, or mass of doughy paste, cooked with a potpie; -- also called dumpling.

Th' impenetrable crust thy teeth defies. --Dryden.

He that keeps nor crust nor crumb. --Shak.

They . . . made the crust for the venison pasty. --Macaulay.

3. (Geol.) The exterior portion of the earth, formerly universally supposed to inclose a molten interior.

4. (Zo["o]l.) The shell of crabs, lobsters, etc.

5. (Med.) A hard mass, made up of dried secretions blood, or pus, occurring upon the surface of the body.

6. An incrustation on the interior of wine bottles, the result of the ripening of the wine; a deposit of tartar, etc. See Beeswing.

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 

Main Entry: crust
Pronunciation: 'kr&st
Function: noun
1 : SCAB 2
2 : an encrusting deposit of serum, cellular debris, and bacteria present over or about lesions in some skin diseases (as impetigo or eczema) —crust verb

crust (krŭst)
n.

1. A hard, crisp covering or surface.
2. An outer layer or coating formed by the drying of a bodily exudate such as pus or blood; a scab.

v. crust·ed, crust·ing, crusts
To cover with, become covered with, or harden into a crust.

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.

crust

see upper crust.