Final answer:
DOS stands for Disk Operating System, which was a prevalent operating system in the early personal computing era, offering a command line interface.
Step-by-step explanation:
The acronym DOS stands for Disk Operating System. DOS was an early operating system that was widely used in personal computers. It provided a command line interface for managing files and running programs. Originally developed by Microsoft, DOS was integral in the operation of early IBM PCs and was a common operating system in the 1980s and early 1990s before the rise of Microsoft Windows.