According to: https://kb.iu.edu/d/agat "To use the Unix trademark, an operating system vendor must pay a licensing fee and annual trademark royalties to The Open Group. Officially licensed Unix operating systems (and their vendors) include macOS (Apple), Solaris (Oracle), AIX (IBM), IRIX (SGI), and HP-UX (Hewlett-Packard). Operating systems that behave like Unix systems and provide similar utilities but do not conform to Unix specification or are not licensed by The Open Group are commonly known as Unix-like systems."
Many will include the *BSDs as a Unix, because their code does directly descend from the original Unix code. But Linux distros generally do not meet either definition of "Unix".