TUI stands for "Text User Interface" not "Terminal User Interface" considering that the point of TUI vs GUI is to distinguish text mode from graphical mode. The word "terminal" isn't really meant to imply text even if quite a few terminal emulators are, indeed, text mode; rather it typically means that the UI is drawn by some other machine than the one you're touching. For example, a very popular Windows Server feature formerly named "Terminal Services" is for GUI terminals, not TUI terminals. A likely source of confusion is the MacOS app named Terminal, which only becomes a terminal in the real sense of the word once you decide to let some other machine draw your UI (ssh, telnet, rlogin, etc.).

But it looks very cool!

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_flux an hour ago | parent | next [-]

On the other hand, there are many elements in the user interface that are not text. In fact, I think it would be quite understandable if one even separated REPLs like bash or octave to be "text user interfaces" while applications that make use of character placement and border special characters "terminal user interfaces", because they use means beyond text stream to communicate with the user. One might even render straight up graphics to a terminal [emulator application].

Even X had a separate application called xterm 42 years ago: the complete X system was not to my knowledge called a terminal system, except perhaps when discussing the dedicated client devices, such as VT1300. Also the term "virtual terminal" as far as I know has always referred to a the kind of interface this application is making use of.

So I think we can just accept that the term is overloaded such that "terminal" refers to both of these situations, as there is no historical precedent to have it exclude the other situation, and the term "terminal-based application" is completely clear to a rational listener.

	▲	nine_k an hour ago \| parent [-]
		A REPL like bash already is not a pure text stream, since readline is used. Zsh, even less so.

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dual_dingo an hour ago | parent | prev [-]

I would argue that a local only session with terminal.app is still a real terminal session because the app is just a terminal for the connection to the MacOS version of getty. In principle, this is not different from having a serial cable between the host and an old-style terminal or encapsulating that connection over a different network like with SSH and telnet etc.