The Collaborative International Dictionary of English v.0.48:

Incrust \In*crust"\, v. t. [imp. & p. p. Incrusted; p. pr. &
   vb. n. Incrusting.] [L. incrustare; pref. in- in + crustare
   to cover with a crust: cf. F. incruster. See Crust.]
   [Written also encrust.]
   [1913 Webster]
   1. To cover or line with a crust, or hard coat; to form a
      crust on the surface of; as, iron incrusted with rust; a
      vessel incrusted with salt; a sweetmeat incrusted with
      sugar.
      [1913 Webster]

            And by the frost refin'd the whiter snow,
            Incrusted hard.                       --Thomson.
      [1913 Webster]

   2. (Fine Arts) To inlay into, as a piece of carving or other
      ornamental object.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

encrust \en*crust"\, v. t.
   To incrust. See Incrust.
   [1913 Webster]

WordNet (r) 3.0 (2006):

encrust
    v 1: cover or coat with a crust [syn: encrust, incrust]
    2: decorate or cover lavishly (as with gems) [syn: encrust,
       incrust, beset]
    3: form a crust or a hard layer [syn: encrust, incrust]