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.