WordNet (r) 3.0 (2006):

small computer system interface
    n 1: interface consisting of a standard port between a computer
         and its peripherals that is used in some computers [syn:
         small computer system interface, SCSI]

The Free On-line Dictionary of Computing (30 December 2018):

Small Computer System Interface
SASI
SCSI

    (SCSI) /skuh'zee/, /sek'si/ The most
   popular processor-independent standard, via a parallel bus,
   for system-level interfacing between a computer and
   intelligent devices including hard disks, floppy disks,
   CD-ROM, printers, scanners, and many more.

   SCSI can connect multiple devices to a single SCSI adaptor
   (or "host adaptor") on the computer's bus. SCSI transfers bits
   in parallel and can operate in either asynchronous or
   synchronous modes.  The synchronous transfer rate is up to
   5MB/s.  There must be at least one target and one
   initiator on the SCSI bus.

   SCSI connections normally use "single ended" drivers as
   opposed to differential drivers.  Single ended SCSI can
   suport up to six metres of cable.  Differential ended SCSI can
   support up to 25 metres of cable.

   SCSI was developed by Shugart Associates, which later became
   Seagate.  SCSI was originally called SASI for "Shugart
   Associates System Interface" before it became a standard.

   Due to SCSI's inherent protocol flexibility, large support
   infrastructure, continued speed increases and the acceptance
   of SCSI Expanders in applications it is expected to hold its
   market.

   The original standard is now called "SCSI-1" to distinguish it
   from SCSI-2 and SCSI-3 which include specifications of
   Wide SCSI (a 16-bit bus) and Fast SCSI (10 MB/s transfer).

   SCSI-1 has been standardised as ANSI X3.131-1986 and
   ISO/IEC 9316.

   A problem with SCSI is the large number of different
   connectors allowed.  Nowadays the trend is toward a 68-pin
   miniature D-type or "high density" connector (HD68) for
   Wide SCSI and a 50-pin version of the same connector (HD50)
   for 8-bit SCSI (Type 1-4, pin pitch 1.27 mm x 2.45 mm).
   50-pin ribbon cable connectors are also popular for internal
   wiring (Type 5, pin pitch 2.54 mm x 2.54 mm).  Apple
   Computer used a 25-pin connector on the Macintosh computer
   but this connector causes problems with high-speed equipment.
   Original SCSI implementations were highly incompatible with
   each other.

   ASPI is a standard Microsoft Windows interface to SCSI
   devices.

   Usenet newsgroup: news:comp.periphs.scsi.

   SCSI Trade Association & FAQ (http://scsita.org/).

   ["System" or "Systems"?]

   (1999-03-30)