In Mathematica, we can often get very special symbols by typing
esc ... esc or
\[...], such as the Wolf or Mathematica's logo. Is it possible to define new special symbols like those and then use them as
It depends on what you mean by a "special symbol".
If you just want an Esc ... Esc shortcut to insert some predetermined expression, you can use an input alias.
Any Unicode character in the basic multilingual plane can be entered by typing
xxxx is its code point in hexadecimal. You can of course define a more memorable input alias for it.
If you really want something that behaves like a character but has a custom glyph, then the answer is "not really". You would have to find an unused code point in the Private Use Area and edit Mathematica's font files to add a glyph for that code point. Which means these notebooks would only display correctly on your machine.