1 on a loaf of bread/pie
ADJ. thick, thin | pastry, pie
PHRASES a crust of bread We saved a few crusts of bread for the birds.
2 hard layer on the outside of sth
ADJ. thick, thin
VERB + CRUST form The mud had formed a thick crust on the surface of the road.
CRUST + VERB form Put the lid on properly, or a crust will form on the paints.
PREP. ~ of a thin crust of ice
PHRASES the earth's crust