Cee is unix because operating systems are languages and languages are operating systems.
Of course today's *nix operating systems such as Linux, OpenBSD, Solaris, are more than just Cee.. but the metaphor still stands.
As another example: UCSD Pascal was an operating system, but also a language.
In some cases a LanguageIsAnOs, but CeeLanguage isn't generally considered to qualify.
- In his defense, the ANSI C standard library is a proper subset of the original Unix API, if I recall correctly. Most people do not consider C to be "C" without it (more generally, most folks don't consider a language a "true language" without a standard library either; the failure of the Oakwood Conventions committee to settle on a standard library for Oberon probably did more to kill it than anything else, for example). So, in some real sense, C really does imply Unix.
- I'm not convinced that the origin of a language should be relevant to the question of whether a particular LanguageIsAnOs. I'd point one more towards those languages that are defined along with large runtime frameworks that have concurrency and communication models.