WordNet (r) 3.0 (2006):

MS-DOS
    n 1: an operating system developed by Bill Gates for personal
         computers [syn: MS-DOS, Microsoft disk operating
         system]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

MSDOS
       MicroSoft Disk Operating System (MS, OS, PC)


The Jargon File (version 4.4.7, 29 Dec 2003):

MS-DOS
 /M?S?dos/, n.

    [MicroSoft Disk Operating System] A clone of CP/M for the 8088 crufted
    together in 6 weeks by hacker Tim Paterson at Seattle Computer Products,
    who called the original QDOS (Quick and Dirty Operating System) and is said
    to have regretted it ever since. Microsoft licensed QDOS in order to have
    something to demo for IBM on time, and the rest is history. Numerous
    features, including vaguely Unix-like but rather broken support for
    subdirectories, I/O redirection, and pipelines, were hacked into
    Microsoft's 2.0 and subsequent versions; as a result, there are two or more
    incompatible versions of many system calls, and MS-DOS programmers can
    never agree on basic things like what character to use as an option switch
    or whether to be case-sensitive. The resulting appalling mess is now the
    highest-unit-volume OS in history. Often known simply as DOS, which annoys
    people familiar with other similarly abbreviated operating systems (the
    name goes back to the mid-1960s, when it was attached to IBM's first disk
    operating system for the 360). The name further annoys those who know what
    the term operating system does (or ought to) connote; DOS is more
    properly a set of relatively simple interrupt services. Some people like to
    pronounce DOS like ?dose?, as in ?I don't work on dose, man!?, or to
    compare it to a dose of brain-damaging drugs (a slogan button in wide
    circulation among hackers exhorts: ?MS-DOS: Just say No!?). See mess-dos.


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

Microsoft Disk Operating System
Microsoft DOS
MS-DOS

    /M S doss/ (Or "MS-DOS", "PC-DOS",
   "MS-DOG", "mess-dos") Microsoft Corporation's clone of
   the CP/M disk operating system for the 8088 crufted
   together in 6 weeks by hacker Tim Paterson, who is said to
   have regretted it ever since.

   MS-DOS is a single user operating system that runs one
   program at a time and is limited to working with one megabyte
   of memory, 640 kilobytes of which is usable for the
   application program.  Special add-on EMS memory boards
   allow EMS-compliant software to exceed the 1 MB limit.
   Add-ons to DOS, such as Microsoft Windows and DESQview,
   take advantage of EMS and allow the user to have multiple
   applications loaded at once and switch between them.

   Numerous features, including vaguely Unix-like but rather
   broken support for subdirectories, I/O redirection and
   pipelines, were hacked into MS-DOS 2.0 and subsequent
   versions; as a result, there are two or more incompatible
   versions of many system calls, and MS-DOS programmers can
   never agree on basic things like what character to use as an
   option switch ("-" or "/").  The resulting mess became the
   highest-unit-volume operating system in history.  It was
   used on many Intel 16 and 32 bit microprocessors and IBM
   PC compatibles.

   Many of the original DOS functions were calls to BASIC (in
   ROM on the original IBM PC), e.g. Format and Mode.  People
   with non-IBM PCs had to buy MS-Basic (later called
   GWBasic).  Most version of DOS came with some version of
   BASIC.

   Also know as PC-DOS or simply DOS, ignoring the fact that
   there were many other OSes with that name, starting in the
   mid-1960s with IBM's first disk operating system for the
   IBM 360.

   [Jargon File]

   (2007-05-21)