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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

Here to break down all the do’s and don’ts of making shortcrust pastry is Bridget Vickers, senior chef-instructor at the Institute of Culinary Education’s Los Angeles campus.

From Salon • Oct. 15, 2025

The venue, on the outskirts of Shrewsbury, also features a fully restored cottage for newlyweds who get married there, as well as multiple areas where couples can say their "I do's".

From BBC • Oct. 7, 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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