It is the only version of the System V variant of UNIX available as open source.
From the en.wikipedia.org
Unix was the first place I encountered the simplification to a single character.
From the en.wikipedia.org
Unix was adapted for use on any and every computer from mainframes to desktops.
From the bbc.co.uk
Unix-like links to Unix in the first sentence, so I don't think it's necessary.
From the en.wikipedia.org
Unix-like operating systems generally cannot function if the C library is erased.
From the en.wikipedia.org
Monitor and respond to related problem tickets assigned to UNIX Access Management.
From the jobview.monster.com
Unix is a computer operating system originally developed in 1969 by Bell Labs.
From the sltrib.com
When OS X came out there was the added advantage of an OS that was UNIX based.
From the nzherald.co.nz
In 1969, the UNIX operating system was created by Dennis Ritchie and Ken Thompson.
From the en.wikipedia.org
More examples
Trademark for a powerful operating system
File:Unix history-simple.png|250px|thumb|Evolution of Unix and Unix-like systems default
UNIX is a trademarked name that refers to the operating system most often used by web servers, and is popular because of its portability, its use of plain text, and its time-sharing configuration for multiple users.
A computer operating system (the basic software running on a computer, underneath things like word processors and spreadsheets). UNIX is designed to be used by many people at the same time (it is multi-user) and has TCP/IP built-in. It is the most common operating system for servers on the Internet.
A very large and constantly evolving language with several alternative and largely incompatible syntaxes, in which anyone can define anything any way they choose, and usually do. ...
Computer operating system, developed by Bell Laboratories. Mostly used for servers and web servers.
A text-based, multitasking Operating System suitable for Web and network administration. Unix has spawned numerous popular spinoffs, including Linux and FreeBSD. ...
Is a group of operating systems that are descended from the original Unix operating system developed in the 1970s. This includes Solaris, HP-UX, Linux, Mac OS X, and many others.
This is an operating system developed by AT&T. It's big push it that it allows one server to service many different end users at one time.