Right, "unix" roughly means - Derived from Bell Labs unix source - Legally allowed to use the UNIX trademark (AKA certified Unix) - A unix-shaped OS (similar

Right, "unix" roughly means - Derived from Bell Labs unix source - Legally allowed to use the UNIX trademark (AKA certified Unix) - A unix-shaped OS (similar but not 100% the same as POSIX complacence) and those things are basically independent. Most GNU/Linux are unix-likes but not derived from original unix code or certified, but there's been 1-2 that did get certified. The BSDs are (now quite distantly ) derived from unix source but not certified (although ex. UnixWare is IIRC). Solaris was all 3 but OpenSolaris and now illumos are obviously unix-like and still based on the original code but not certified UNIX™. (Take all this with a grain of salt; I'm typing this all from memory and IANAL)