Source : Free On-Line Dictionary of Computing

data mart
     
         A type of {data warehouse} designed primarily to
        address a specific function or department's needs, as opposed
        to a data warehouse which is traditionally meant to address
        the needs of the organisation from an enterprise perspective.
        In addition, a data mart often uses {aggregation} or
        summarisation of the data to enhance query performance.
        However, it is important to maintain the ability to access the
        underlying base data to enable {drill-down analysis} as
        necessary.
     
        (1998-04-24)