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Synonyms

DOS

1 American  
[daws, dos] / dɔs, dɒs /

noun

Computers.
  1. any of several single-user, command-driven operating systems for personal computers, especially MS DOS.


DOS 2 American  

abbreviation

  1. Department of State.


DoS 3 American  
[daws, dos, dee-oh-es] / dɔs, dɒs, ˈdiˌoʊˈɛs /

abbreviation

  1. Computers. denial-of-service.

    DoS protection for web servers.


DOS British  
/ dɒs /

acronym

  1. disk-operating system, often prefixed, as in MS-DOS and PC-DOS; a computer operating system

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of DOS

d(isk) o(perating) s(ystem)

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Here are some do’s and don’ts to remember when using AI for performance reviews:

From The Wall Street Journal • Feb. 24, 2026

The DMA is part of the European Union's bolstered legal armoury that seeks to make the digital sphere fairer with a list of do's and don'ts for Big Tech.

From Barron's • Nov. 18, 2025

A professor at Kabul University told the BBC that under such circumstances, they are forced to prepare textbook chapters themselves, taking into account the do's and don'ts imposed by the Taliban government.

From BBC • Sep. 18, 2025

But in our hour-long conversation, Topol discussed several do’s and don’ts for anyone seeking to make 80 the new 50.

From Los Angeles Times • Jun. 6, 2025

After practice, everybody came over to me, doing the best they could to hold their words in but sending me all their what did you do's with their eyes.

From "Ghost" by Jason Reynolds

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