A rind; a hardened outer crust. Obsolete.

A more or less hard coating, concretion, or deposit on the surface of anything; an incrustation.

figurative.

A thin crust or coating. Cf. scurf, n.1 4.

gen. An outer covering or husk; esp. a superficial crust or incrustation. Obsolete exc. dialect.

The quality or condition of being crusty. concrete a crusty formation, incrustation.

A crust or hard coating formed naturally on the surface of an object; esp. a calcareous or crystalline concretion or deposit.

transferred. concrete. A thin crust of extraneous matter formed on the surface of metals; hence, a coating of foreign matter on other substances.

concrete. That which is deposited by the action of encrusting; an outer encrusted layer or shell. Also figurative.