The Collaborative International Dictionary of English v.0.48:

Invisibility \In*vis`i*bil"i*ty\, n.; pl. Invisibilities. [L.
   invisibilitas: cf. F. invisibilit['e].]
   The state or quality of being invisible; also, that which is
   invisible. "Atoms and invisibilities." --Landor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

invisibility
    n 1: the quality of not being perceivable by the eye [syn:
         invisibility, invisibleness] [ant: visibility,
         visibleness]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "invisibility":
   burial, burying, clouding, concealedness, concealment, covering,
   covering up, covertness, darkening, deception, evanescence,
   hiddenness, hiding, impalpability, imperceptibility,
   imponderability, intangibility, interment, masking, mystification,
   obscuration, obscurement, occultation, putting away, screening,
   secrecy, secretion, subterfuge, tenuousness, uncommunicativeness