Source : Free On-Line Dictionary of Computing

Wide SCSI
     
         A variant on the {SCSI-2} interface.  It
        uses a 16-bit bus - double the width of the original {SCSI}-1
        - and therefore cannot be connected to a SCSI-1 bus.  It
        supports transfer rates up to 20 MB/s, like {Fast SCSI}.
     
        There is also a SCSI-2 definition of Wide-SCSI with a 32 bit
        data bus.  This allows up to 40 megabytes per second but is
        very rarely used because it requires a large number of wires
        (118 wires on two connectors).  Thus Wide SCSI usually means
        16 bit-wide SCSI.
     
        (1995-04-21)