The Collaborative International Dictionary of English v.0.48:

Mountebank \Mount"e*bank\, v. t.
   To cheat by boasting and false pretenses; to gull. [R.]
   --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mountebank \Mount"e*bank\, v. i.
   To play the mountebank.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mountebank \Mount"e*bank\, n. [It. montimbanco, montambanco;
   montare to mount + in in, upon + banco bench. See Mount,
   and 4th Bank.]
   1. One who mounts a bench or stage in the market or other
      public place, boasts of his skill in curing diseases, and
      vends medicines which he pretends are infallible remedies;
      a quack doctor.
      [1913 Webster]

            Such is the weakness and easy credulity of men, that
            a mountebank . . . is preferred before an able
            physician.                            --Whitlock.
      [1913 Webster]

   2. Any boastful or false pretender; a charlatan; a quack.
      [1913 Webster]

            Nothing so impossible in nature but mountebanks will
            undertake.                            --Arbuthnot.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mountebank
    n 1: a flamboyant deceiver; one who attracts customers with
         tricks or jokes [syn: mountebank, charlatan]