The Collaborative International Dictionary of English v.0.48:

Immateriality \Im`ma*te`ri*al"i*ty\, n.; pl. Immaterialities.
   [Cf. F. immat['e]rialit['e].]
   The state or quality of being immaterial or incorporeal; as,
   the immateriality of the soul.
   [1913 Webster]

WordNet (r) 3.0 (2006):

immateriality
    n 1: complete irrelevance requiring no further consideration
         [ant: materiality]
    2: the quality of not being physical; not consisting of matter
       [syn: immateriality, incorporeality] [ant: corporality,
       corporeality, materiality, physicalness]