[dspillett]

Or sometimes Terminal, I've seen them used interchangeably though I find “Text” is more common.

Usually TUI is used in a way that implies not just a basic command line interface: something like a GUI (buttons, dialogs, navigable lists, frames, interactive text editing, etc) just drawn using “text” elements so it works via a terminal console. I've seen some people refer to almost any CLI or REPL as a TUI but while they match the words of the acronym (they are user interfaces based on text) I think this is incorrect and TUI refers to a more specific sub-set of text-based interfaces.

See https://en.wikipedia.org/wiki/Text-based_user_interface for more references.