noun. the outer layer of the Earth.
noun. ['ˈkrʌst'] the outer layer of the Earth.
noun. ['ˈkrʌst'] the trait of being rude and impertinent; inclined to take liberties.
verb. ['ˈkrʌst'] form a crust or form into a crust.
noun. ['ˈkrʌst'] a hard outer layer that covers something.