Two schools of philosophy gained dominance in our century: Existentialism and LinguisticAnalysis (Analytic and Linguistic Philosophy). The first deals with man's responsibility for his acts from the point of view of a posited free will. The second proposes that since communication is essential for human enterprise, language --as the principal means of communication-- ought to be unambiguous. Of course, ambiguity is a desirable and actually essential attribute of the arts, as exemplified by Monalisa's smile and poetry's similes.
It is most ironic that Aristotle --albeit unwittingly-- was the source of one outstanding confusing concept: METAPHYSICS. In one of his treatises he dealt on PHYSICS, and also on other subjects. The latter group was much later refered to as "Metaphysics," the intention being that they were written AFTER (meta) "Physics."
Now, those writings included musings on Being (what exists); for that reason, Metaphysics came to be include Ontology, which is the study of Being. I should add that as Physics is the study of the material aspects of Nature, Metaphysics could be understood as the thoughts on the concept of "Physics" itself --and its ultimate significance, such as thinking about "thinking" may be called "Metathinking," a central concept in Dynamic-Scientific Phylosophy.
Still, actually the most common application for the term "metaphysics" refers to concepts which cannot be grasped by the senses, i.e., which are theological, such as the religious explications on the "soul," a subject also dealt upon in Aristotle's "Metaphysics."

The unqualified use of that word should therefore be avoided. In the same vein, the usage of words with the utmost clarity is strongly recommend, avoiding strictly personal expressions, such as, "I opine," "I believe," "I think," in favor of more precise ones like "studies have shown that...," "it stands to reason that...," and so forth.