Stallman's definition is correct. The operating system for everyone else includes the userland and libc. Luckily this is what made LX and the Windows equivalent possible, though.
Ok then my second point stands. If I bought a new car and you said "Nice wheels" (is this slang still in use?) and I said "What you're referring to as wheels is actually car/wheels", you'd think I was an idiot.
If someone says just "Linux" they colloquially mean "Linux based operating systems" or perhaps even "Linux based operating systems like those in the most common distributions".
If I say "IE only runs on Windows", people dont argue that it doesn't run on Windows 3.11. They just know that "Windows" means "modern Windows" in this case, or at the very least, the implication that IE DOESNT run on competing operating systems. I mean, if I'm in a debate about Microsft vs Apple and I say "but for DirectX 12 and games you need Windows!" - here I specifically mean Windows 10, but "Windows" is enough to distinguish it from competitors.
If I say a game is for "Windows and Linux" or "Windows and Mac, but not Linux", its safe to say you understood what I'm talking about. And arguing otherwise means you're being pedantic.
If we're not currently in a discussion about differences between kernels or even libc implementations (in those discussions, it's safe to assume we're not using a colloquial definition), then it is safe to say that "Linux" means "Linux based operating system"
