system
Given the following post, respond as if you're commenting on Reddit:
human
Does the Greek letter π have any meaning in math other than the number 3.14...

I have seen it in places where it seems that it means something else.  I may have seen it in logic, too.
gpt
The prime counting function would be the obvious example of another use.

Its also used at the limit value for the proportion of time spent at a particular state in a markov chain.

The symbol is just a symbol. Its not magically tied to the circle constant.