[syn: intangible, nonphysical]
The Collaborative International Dictionary of English v.0.48:
Intangible \In*tan"gi*ble\, a. [Pref. in- not + tangible: cf. F.
   intangible.]
   Not tangible; incapable of being touched; not perceptible to
   the touch; impalpable; imperceptible. --Bp. Wilkins.
   [1913 Webster]
         A corporation is an artificial, invisible, intangible
         being.                                   --Marshall.
   -- In*tan"gi*ble*ness, n. -- In*tan"gi*bly, adv.
   [1913 Webster]
WordNet (r) 3.0 (2006):
intangible
    adj 1: (of especially business assets) not having physical
           substance or intrinsic productive value; "intangible
           assets such as good will" [ant: tangible]
    2: incapable of being perceived by the senses especially the
       sense of touch; "the intangible constituent of energy"- James
       Jeans [syn: intangible, impalpable] [ant: tangible,
       touchable]
    3: hard to pin down or identify; "an intangible feeling of
       impending disaster"
    4: lacking substance or reality; incapable of being touched or
       seen; "that intangible thing--the soul" [syn: intangible,
       nonphysical]
    n 1: assets that are saleable though not material or physical
         [syn: intangible, intangible asset]
Moby Thesaurus II by Grady Ward, 1.0:
78 Moby Thesaurus words for "intangible":
   aerial, aeriform, airy, asomatous, astral, atomic, bodiless,
   corpuscular, decarnate, decarnated, dim, discarnate, disembodied,
   eluding, elusive, embryonic, ethereal, evanescent, evasive,
   extramundane, fleeting, germinal, ghostly, granular, immaterial,
   impalpable, imperceptible, imponderable, imprecise, inappreciable,
   incorporate, incorporeal, indefinite, indiscernible, infinitesimal,
   insensible, insubstantial, invisible, microcosmic, microscopic,
   molecular, nonmaterial, nonphysical, nonsubstantial, obscure,
   occult, otherworldly, phantom, psychic, rare, shadowy, slender,
   slight, spiritual, subatomic, supernatural, tenuous, thin,
   transmundane, ultramicroscopic, unapparent, unappreciable,
   unconcrete, unearthly, unembodied, unextended, unfleshly,
   unobservable, unperceivable, unphysical, unseeable, unsolid,
   unsubstanced, unsubstantial, unworldly, vague, vaporous,
   weightless