Source : Free On-Line Dictionary of Computing

IDL
     
        1. Interactive Data analysis Language.  {Xerox}.  Built on
        {Interlisp-D}.
     
        2. {Interface Description Language} (Snodgrass, UNC, Arizona).
     
        3. {Interface Definition Language} ({SunSoft}, {OMG}).
     
        4. {Interactive Data Language} ({Research Systems}).