I've seen that some platforms support the modifier key Hyper (separate from Ctrl, Alt, Shift, Super/Cmd/Windows modifier keys).

While this is not a common modifier, It's available in X11, and I read something to to suggest macOS supports it too.

Which operating systems support a 5th (Hyper) modifier key?

  • I'm guessing that if X11 has it, it's probably because some weird terminal / obscure Unix system way-back-when had such a key, so there's a flag "just in case". Given that virtually nothing I know nowadays has such a thing (discounting the Fn key that many laptops have to handle keys with duplicate functions), I don't think it's something you'd want to use even if the OS supports it.
    – TripeHound
    Jul 19, 2019 at 13:15
  • There are references online for setting up Hyper key on macOS for eg, so assumed this wasn't just X11.
    – ideasman42
    Jul 19, 2019 at 22:18
  • macOS is based on Unix so that's more-or-less to be expected.
    – TripeHound
    Jul 19, 2019 at 22:40

1 Answer 1


The Hyper modifier key is defined in the Space-cadet keyboard. This type of keyboards used in the MIT Lisp machines which ran some dedicated operating systems. These OSes were written from the ground up in Lisp programming language, such as Genera.


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