This is true, and I'm often peeved by exactly the same conflation. However, in cases like Clojure, where there's (as far as I know) really only a single implem

This is true, and I'm often peeved by exactly the same conflation. However, in cases like Clojure, where there's (as far as I know) really only a single implementation out there to be used, it's easy to blur the lines. Python is getting less so thanks to PyPy, though my perception of that is that thus far it's more on an "awareness" level than it actually being in widespread production use (though hopefully as it matures we'll see more of the latter). The languages mentioned in this blog post present an interesting sort of in-between case though, since at some level you could almost regard them as being a collection of implementations of the same language (Lisp), rather than as actually distinct languages. I realize that's stretching some definitions a bit, but I think there's kind of a continuous spectrum there between "different language" and "different implementation of the same language". I mean, GCC implements extensions to C that aren't in the C standard and aren't (to my knowledge) supported in, say, MSVC; some refer to this as "GNU C", though I'd guess most non-language-lawyers looking at it would probably still call it "C" anyway. On the whole though, I agree with you.