The name is TeXmacs - but "Notice that TeXmacs is not based on TeX/LaTeX." I wonder why they chose that name.
It isn't compatible with TeX/LaTeX but it does serve the same purpose (and converters are available). I don't disagree it's a weak name, though. The naming implies some sort of rich LaTeX editor plugin for emacs - I need Mike Meyers to leap out and say "Texmacs is neither LaTeX nor Emacs - discuss."
Neither on emacs and nor it’s a Mac first app. Probably the most misleading app name ever.