The Collaborative International Dictionary of English v.0.48:

Banker \Bank"er\ (b[a^][ng]k"[~e]r), n.[See the nouns Bank and
   the verbs derived from them.]
   1. One who conducts the business of banking; one who,
      individually, or as a member of a company, keeps an
      establishment for the deposit or loan of money, or for
      traffic in money, bills of exchange, etc.
      [1913 Webster]

   2. A money changer. [Obs.]
      [1913 Webster]

   3. The dealer, or one who keeps the bank in a gambling house.
      [1913 Webster]

   4. A vessel employed in the cod fishery on the banks of
      Newfoundland. --Crabb. --J. Q. Adams.
      [1913 Webster]

   5. A ditcher; a drain digger. [Prov. Eng.]
      [1913 Webster]

   6. The stone bench on which masons cut or square their work.
      --Weale.
      [1913 Webster]

WordNet (r) 3.0 (2006):

banker
    n 1: a financier who owns or is an executive in a bank
    2: the person in charge of the bank in a gambling game