Source : Free On-Line Dictionary of Computing

usability
     
         The effectiveness, efficiency, and satisfaction
        with which users can achieve tasks in a particular environment
        of a product.  High usability means a system is: easy to learn
        and remember; efficient, visually pleasing and fun to use; and
        quick to recover from errors.
     
        {(http://www.orrnet.com/)}.
     
        (1999-04-01)