Source : WordNet®

DoS
     n 1: the federal department in the UnitedStates that sets and
          maintains foreign policies; "the Department of State was
          created in 1789" [syn: {Department of State}, {State
          Department}, {State}]
     2: an operating system that is on a disk [syn: {disk operating
        system}]

Source : Free On-Line Dictionary of Computing

DOS
     
         1. The common abbreviation for {MS-DOS}.
     
        2. {IBM}'s {Disk Operating System}.
     
        3. Any {disk operating system}.
     
        (2001-03-16)