Source : Webster's Revised Unabridged Dictionary (1913)

Incrustation \In`crus*ta"tion\, n. [L. incrustatio: cf. F.
   incrustation. See {Incrust}.]
   1. The act of incrusting, or the state of being incrusted.

   2. A crust or hard coating of anything upon or within a body,
      as a deposit of lime, sediment, etc., from water on the
      inner surface of a steam boiler.

   3. (Arch.) A covering or inlaying of marble, mosaic, etc.,
      attached to the masonry by cramp irons or cement.

   4. (Fine Arts) Anything inlaid or imbedded.

Source : WordNet®

incrustation
     n 1: the formation of a crust [syn: {encrustation}]
     2: a hard outer layer that covers something [syn: {crust}, {encrustation}]
     3: a decorative coating of contrasting material that is applied
        to a surface as an inlay or overlay [syn: {encrustation}]