What does the "cyg" prefix mean?

I've seen so many cyg prefixed things like cygstart, cygpath, cygwin etc., but what exactly does this prefix mean?

Cygnus solutions was a company that provided commercial support for free software, they were founded in 1989 and merged with Redhat in 2000. The name was apparently a recursive acronmy for "Cygnus, your GNU Support".

They were a major contributor to free software, but their most famous project was Cygwin. Cygwin is a posix compatibility layer for Windows and a port of the GNU software stack to said compatibility layer.

Cygwin used the "cyg" prefix as a naming convention for cygwin-specific functionality, for example.

• "/cygdrive/" is used as a path prefix to allow acess to files outside the cygwin root.
• "cygstart" is an application similar to the windows "start" program used to start GUI apps from the command line but integrated with cygwin.
• "cygpath" is a tool to convert between windows paths and posix style paths.

The MSYS2 environment used by the likes of "Git bash", borrows some code and conventions from cygwin (though other conventions are different, for example MSYS2 uses /c for the C: drive rather than /cygdrive/c ) and so you will see "cyg" prefixes there too.