crust

Concise Oxford English Dictionary © 2008 Oxford University Press:
crust/krʌst/

▶noun

• 1 the tough outer part of a loaf of bread.

  ■ a hard, dry scrap of bread.

• 2 a hardened layer or coating on something soft.

  ■ a layer of pastry covering a pie.

• 3 the outermost layer of rock of which a planet consists, especially the part of the earth above the mantle.

• 4 a deposit of tartrates and other substances formed in wine aged in the bottle, especially port.

• 5 Brit. informal a living or livelihood: earning a crust.

▶verb (often as adj. crusted) form into or cover with a crust: crusted port.

– derivatives
crustal adjective (Geology).

– origin ME: from OFr. crouste, from L. crusta ‘rind, shell, crust’.