—n.
1 a the hard outer part of a loaf of bread. b a piece of this with some soft bread attached. c a hard dry scrap of bread. d esp. Austral. sl. a livelihood (what do you do for a crust?).
2 the pastry covering of a pie.
3 a hard casing of a softer thing, e.g. a harder layer over soft snow.
4 Geol. the outer portion of the earth.
5 a a coating or deposit on the surface of anything. b a hard dry formation on the skin, a scab.
6 a deposit of tartar formed in bottles of old wine.
7 a sl. impudence (you have a crust!). b a superficial hardness of manner.
—v.tr. & intr.
1 cover or become covered with a crust.
2 form into a crust.
Derivatives:
crustal adj. (in sense 4 of n.).
Etymology: ME f. OF crouste f. L crusta rind, shell
Useful english dictionary. 2012.