The Collaborative International Dictionary of English v.0.48:

Purser \Purs"er\, n. [See Purse, and cf. Bursar.]
   [1913 Webster]
   1. (Naut.) A commissioned officer in the navy who had charge
      of the provisions, clothing, and public moneys on
      shipboard; -- now called paymaster.
      [1913 Webster]

   2. A clerk on steam passenger vessels whose duty it is to
      keep the accounts of the vessels, such as the receipt of
      freight, tickets, etc.
      [1913 Webster]

   3. Colloquially, any paymaster or cashier.
      [1913 Webster]

   Purser's name (Naut.), a false name. [Slang]
      [1913 Webster]

WordNet (r) 3.0 (2006):

purser
    n 1: an officer aboard a ship who keeps accounts and attends to
         the passengers' welfare