As a physicist who takes an interest in metaphysics, I was shocked to learn that practitioners of metaphysics call themselves metaphysicians. Why not metaphysicists?
My first thought was that unlike meta-mathematics or meta-theory or meta-anything, the case of metaphysics is slightly different. Whereas meta-mathematics is the theoretization of mathematics, metaphysics is not the theoretization of physics. People who are meta-theorizing about physics should probably be called metaphysicists. Instead metaphysics is a 'discpline' of inquiry originating in Aristotle's Metaphysics and bears its name mainly due to that circumstance and maybe the fact that it deals with questions that are not or beyond physical.
However, in this light the choice metaphysician also seems awkward. How would physicians call their form of theoretization about their craft? Then again, their craft is medicine and they would call it meta-medicine maybe. Is that the reason why we call practitioners of metaphisics metaphysicians? or is there a historical reason lurking somewhere? When did the term make its first appearance?