a division of philosophy concerned with ultimate causes and the underlying nature of things; esp ontology
Metaphysics is the enquiry into the ultimate nature of reality. It seeks to determine what genuinely and fundamentally exists, and what existence itself is. It asks whether, in addition to physical reality, such things as deity, abstract objects like numbers, and values such as goodness and beauty, exist in the universe, and if so, in what way — Dr Anthony Grayling
pure or speculative philosophy
informal abstract and impractical theorizing
metaphysician /-ʹzish(ə)n/ noun
[medieval Latin Metaphysica, title of Aristotle's treatise on the subject, from Greek (ta) meta (ta) physika, literally ‘the (works) after the physical (works)’; from its position in his collected works]