It's always possible that I've misinterpreted, but here's how rms put it in
his article "Linux and the GNU System"
(https://www.gnu.org/gnu/linux-and-gnu.html):
'...the version of GNU which is widely used today is often called
“Linux”, and many of its users are not aware that it is basically the GNU
system, developed by the GNU Project.
'There really is a Linux, and these people are using it, but it is just a
part of the system they use. Linux is the kernel...'
I interpreted the word "system" the second paragrah, where he says "just a
part of the system", to be the GNU operating system since the phrase "GNU
system" is linked to a page on the gnu.org web site that explains what the
GNU operating system is.
https://www.gnu.org/philosophy/categories.html#TheGNUsystem
On that page, it says, in reference to Linux being used as the kernel instead
of Hurd, "The result is still a variant of the GNU system."
