DOS

noun7

1. •
   Initialism of disk operating system
2. •
   (Internet) Initialism of denial of service.
3. •
   Initialism of director of studies.
4. •
   Initialism of date of service.
5. •
   Initialism of density of states.
6. •
   Initialism of death on scene.
7. •
   Initialism of date of separation.

noun2

1. •
   (Internet) A denial-of-service attack.
2. •
   A Director of Studies; someone who oversees the scholarly aspects of an institution, including faculty development and curriculum design.

verb1

1. •
   (Internet) To commit a denial-of-service attack against.