An abstract sphere of infinite radius which serves as the imaginary backdrop for celestial objects, and of which the visible sky is one hemisphere.
the figure of the universe as an imaginary sphere whose center is the Earth
The outermost layer of the lithosphere of the Earth.
An outer layer composed of pastry
The top or bottom slice of a loaf of bread; The end piece of a loaf; The heel.
The shell of crabs, lobsters, etc.
The outermost layer of any terrestrial planet.
Nerve, gall.
The external, hardened layer of certain foodstuffs, including most types of bread, fried meat, etc.
A living.
The bread-like base of a pizza.
A more solid, dense or hard layer on a surface or boundary.
To cover with a crust.
To form a crust.