1
- the tough outer part of a loaf of bread面包皮：
a sandwich with the crusts cut off
一个切掉了外皮的三明治
mass noun I tore off several pieces of crust from the loaf.我从面包上撕下了几块皮。
1.1
- a hard, dry scrap of bread干面包片：
a kindly old woman might give her a crust.
一位仁慈的老太太可能会给她一片干面包。
1.2
- informal a living or livelihood〈非正式〉生活, 生计：
I've been earning a crust wherever I can.
我一直在到处谋生。
1.3
- a layer of pastry covering a pie馅饼皮。
1.4
- a hardened layer, coating, or deposit on the surface of something, especially something soft（尤指软物表面的）硬外皮, 外壳：
a crust of snow
雪壳。
1.5
- the outermost layer of rock of which a planet consists, especially the part of the earth above the mantle（尤指地球等行星的）地壳：
the earth's crust
地球的地壳
mass noun at the mid-ocean ridge new crust is formed.新的地壳在洋中脊形成。
1.6
- a deposit of tartrates and other substances formed in wine aged in the bottle, especially port（尤指波尔图葡萄酒瓶中的）酸式酒石酸钾沉淀。
no obj.
1- form into a hard outer layer形成（或结成）硬皮（或硬壳）：
the blisters eventually crust over.
水疱终于结痂了。
1.1
- with obj. cover with a hard outer layer用硬皮（或硬壳）覆盖：
the burns crusted his cheek.
他的脸上长满了络腮胡子。
派生词
crustal
adjective 限用于名词表地质意义时词源
Middle English: from Old French crouste, from Latin crusta 'rind, shell, crust'.