What does OSS stand for in computer terms?
Open Source Software.
There are three main terms when referring to a computing machine without multiple operating systems (OSs). "Dual boot" OSs offer the operator a choice between them at start-up. There are also "virtual machines" in which the primary OS is running while the second is open in a separate window simultaneously. The third is a machine with a "hard partition" with both OSs installed in two separate parts of the disk.