The Collaborative International Dictionary of English v.0.48:

Incorporeal \In`cor*po"re*al\, a. [Pref. in- not + corporeal:
   cf. L. incorporeus. Cf. Incorporal.]
   [1913 Webster]
   1. Not corporeal; not having a material body or form; not
      consisting of matter; immaterial.
      [1913 Webster]

            Thus incorporeal spirits to smaller forms
            Reduced their shapes immense.         --Milton.
      [1913 Webster]

            Sense and perception must necessarily proceed from
            some incorporeal substance within us. --Bentley.
      [1913 Webster]

   2. (Law) Existing only in contemplation of law; not capable
      of actual visible seizin or possession; not being an
      object of sense; intangible; -- opposed to corporeal.
      [1913 Webster]

   Incorporeal hereditament. See under Hereditament.

   Syn: Immaterial; unsubstantial; bodiless; spiritual.
        [1913 Webster]

WordNet (r) 3.0 (2006):

incorporeal
    adj 1: without material form or substance; "an incorporeal
           spirit" [syn: incorporeal, immaterial] [ant:
           corporeal, material]

Moby Thesaurus II by Grady Ward, 1.0:

100 Moby Thesaurus words for "incorporeal":
   Masan, airy, apparition, appearance, asomatous, astral,
   astral spirit, banshee, bodiless, control, decarnate, decarnated,
   departed spirit, discarnate, disembodied, disembodied spirit,
   duppy, dybbuk, ectoplasmic, eidolon, ethereal, etheric,
   extramundane, form, ghost, ghostish, ghostlike, ghostly, ghosty,
   grateful dead, guide, hant, haunt, idolum, immaterial,
   immateriality, impalpable, imponderable, incorporate,
   incorporeal being, incorporeity, insubstantial, intangible, larva,
   lemures, manes, materialization, metaphysical, nonmaterial,
   nonphysical, nonsubstantial, occult, oni, otherworldly, phantasm,
   phantasma, phantasmal, phantasmic, phantom, phantomic, phantomlike,
   poltergeist, presence, psychic, revenant, shade, shadow, shadowy,
   shape, shrouded spirit, specter, specterlike, spectral,
   spectral ghost, spirit, spiritual, spook, sprite, supernatural,
   theophany, transmundane, unconcrete, unearthly, unembodied,
   unextended, unfleshly, unphysical, unsolid, unsubstanced,
   unsubstantial, unsubstantiality, unworldly, vision,
   walking dead man, wandering soul, weightless, wraith, wraithlike,
   wraithy, zombie