Source : WordNet®

command line interface
     n : a user interface in which you type commands instead of
         choosing them from a menu or selecting an icon [syn: {CLI}]

Source : Free On-Line Dictionary of Computing

command line interface
     
         A means of communication between a
        {program} and its {user}, based solely on textual input and
        output.  Commands are input with the help of a {keyboard} or
        similar device and are interpreted and executed by the
        program.  Results are output as text or graphics to the
        {terminal}.
     
        Command line interfaces usually provide greater flexibility
        than {graphical user interfaces}, at the cost of being harder
        for the novice to use.  Consequently, some {hackers} look down
        on GUIs as designed {For The Rest Of Them}.
     
        (1996-01-12)