Source : Free On-Line Dictionary of Computing

D-shell connector
     
         One of the family of connectors: DA-15, {DB-25},
        DC-37, DD-50, {DE-9}, and DEH-15 [VGA].  The "D" is the shape
        of the shell, the next letter determines connector size, and
        the number is the maximum pin count.
     
        (1999-12-08)