A system software component that is external to the operating system kernel. If the phrase is used to refer to the operating system itself, it is redundant because an operating system "is" software.

An operating system that is designed for a server. Normally, it is a complete operating system with file, task and job management; however, with some earlier products, it was a separate component that ...

Lauded for avoiding the typical vague, high-level survey approach found in many texts, earlier editions of this bestselling book removed the mystery by explaining the internal structure of an ...