Someone that believes the middle of a political spectrum is the difference between the two most popular sides, regardless of those sides positions in the actual political spectrum; i.e. someone that believes liberals and conservatives should work together and compromise in order to not be too left or too right, despite both of those ideologies being inherently far right wing.
I.e. “let’s listen to what Nazis have to say and give them a place in government”
You have, you’re on a reddit clone. Reddit, especially r/politics is centrism defined, including the ever rightward shift it has taken that follows the natural path of centrism.