metaphysics and metaphysical

are so often used as quasi-learned and vaguely depreciatory substitutes for various terms, for theory and theoretical, subtle(ty), (the) supernatural , occult(ism), obscure and obscurity, philosphy and philosophic, academic(s), and so forth, that it is pardonable to forget that they have a real meaning of their own, especially as the usual resource of those who suddenly realize that their notion of a word’s meaning is hazy--an appeal to its etymology--will not serve. It is agreed that the part of Aristotle’s works that treated of metaphysical questions stood after more philosophical Greek here the part concerned with physics and here, and that the word’s etymology is therefore devoid of significance. It is indeed actually misleading if it suggests the inference, as it has to some, that m. is ‘the science of things transcending what is physical or natural’. Even Saintsbury, for instance, though admitting some justice in the criticism of the label ‘metaphysical’ invented by Dryden and adopted by Johnson for Donne, Crowley, and their school, maintained that it was ‘not inappropriately used for the habit, common to this school of poets, of always seeking to express something after, something behind, the obvious first sense and suggestion of a subject’.

Metaphysics is the branch of philosophy that deals with the ultimate nature of things, or considers the questions, What is the world of things we know? (ontology) and, How do we know it? (epistemology), though some philosophers would confine the term to the first. Such being the subject of Metaphysics, it is not wonderful, in view of the infinity of theories and subtlety of arguments evoked, that it should have come by some or all of the wrong acceptations mentioned above.

H.W. Fowler
A Dictionary of Modern English Usage
2nd Edition