ADJECTIVE (3)

1. pertaining to or of the nature of metaphysics;
- Example: "metaphysical philosophy"

2. without material form or substance;
- Example: "metaphysical forces"

3. highly abstract and overly theoretical;
- Example: "metaphysical reasoning"

The Collaborative International Dictionary of English v.0.48:

Metaphysical \Met`a*phys"ic*al\, a. [Cf. F. m['e]taphysique. See
   Metaphysics.]
   1. Of or pertaining to metaphysics.
      [1913 Webster]

   2. According to rules or principles of metaphysics; as,
      metaphysical reasoning.
      [1913 Webster]

   3. Preternatural or supernatural. [Obs.]
      [1913 Webster]

            The golden round
            Which fate and metaphysical aid doth seem
            To have thee crowned withal.          --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

metaphysical
    adj 1: pertaining to or of the nature of metaphysics;
           "metaphysical philosophy"
    2: without material form or substance; "metaphysical forces"
    3: highly abstract and overly theoretical; "metaphysical
       reasoning"

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "metaphysical":
   Cyrenaic, Eleatic, Epicurean, Megarian, Stoic, anagogic, animist,
   animistic, atomistic, bodiless, cabalic, cabalistic, cosmotheistic,
   discarnate, eclectic, empirical, esoteric, eudaemonistic,
   existential, hedonic, hedonist, hedonistic, humanist, humanistic,
   idealistic, incorporeal, instrumentalist, insubstantial,
   materialistic, mechanistic, metaphysic, monistic, mysterious,
   mystic, naturalistic, nominalist, nonmaterial, nonphysical,
   numinous, occult, panlogistical, pantheistic, positivist,
   positivistic, pragmatic, pragmatist, preternatural, rationalistic,
   realist, realistic, scholastic, sensationalistic, spiritual,
   superhuman, superior, supermundane, supernatural, supramundane,
   supranatural, syncretistic, theistic, theosophical, theosophist,
   transcendent, transcendental, transcendentalist,
   transcendentalistic, unearthly, unfleshly, unphysical, utilitarian,
   vitalistic, voluntarist, voluntaristic