Definition of "DOS"

DOS

/dɒs/

proper noun
1. (computing, historical) Acronym of Disk Operating System, a family of disk-based operating systems.
  Quotations
  Next, using your word processor or the DOS text editor, you can edit your AUTOEXEC.BAT file.
  1993, Kris A. Jamsa, DOS: The Complete Reference, McGraw–Hill Osborne Media
  One way to do that is to turn the PC off and turn it back on again. Then, the PC performs its self-test and boots DOS.
  1993, Doug Lowe, The Only DOS Book You'll Ever Need, Mike Murach & Associates Incorporated, page 95
2. (US politics) Initialism of Department of State.
noun
plural DOSes
1. (military) Initialism of date of service.
2. (military) Initialism of date of separation.
3. (computing, Internet) Initialism of denial of service.
4. (sciences) Initialism of density of states.
5. (education) Initialism of director of studies.