Definition - What does UNIX 98 mean?
UNIX 98 is an Open Group Specification. It is compliant with the Single UNIX Specification, version 2.
Techopedia explains UNIX 98
UNIX is an operating system (OS) formulated in 1969 at Bell Labs as an interactive time-sharing system. It was never a proprietary OS and is not owned by the leading computer companies. UNIX also is written in a standard language and is comprised of many popular ideas, which led UNIX to become the primary available open standard OS.