Source : Webster's Revised Unabridged Dictionary (1913)

Bunko \Bun"ko\, n. [Sf. Sp. banco bank, banca a sort of game at
   cards. Cf. {Bank} (in the commercial sense).]
   A kind of swindling game or scheme, by means of cards or by a
   sham lottery. [Written also {bunco}.]

   {Bunko steerer}, a person employed as a decoy in bunko.
      [Slang, U.S.]