the hard external coat or covering of anything; the hard exterior surface or outer shell; an incrustation; as, a crust of snow.-the hard exterior or surface of bread, in distinction from the soft part or crumb; or a piece of bread grown dry or hard.-the cover or case of a pie, in distinction from the soft contents.-the dough, or mass of doughy paste, cooked with a potpie; -- also called dumpling.-the exterior portion of the earth, formerly universally supposed to inclose a molten interior.-the shell of crabs, lobsters, etc.-a hard mass, made up of dried secretions blood, or pus, occurring upon the surface of the body.-an incrustation on the interior of wine bottles, the result of the ripening of the wine; a deposit of tartar, etc. see beeswing.-to cover with a crust; to cover or line with an incrustation; to incrust.-to gather or contract into a hard crust; to become incrusted.