The Collaborative International Dictionary of English v.0.48:

Homogeneousness \Ho`mo*ge"ne*ous*ness\, n.
   Sameness 9kind or nature; uniformity of structure or
   material.
   [1913 Webster]

WordNet (r) 3.0 (2006):

homogeneousness
    n 1: the quality of being similar or comparable in kind or
         nature; "there is a remarkable homogeneity between the two
         companies" [syn: homogeneity, homogeneousness] [ant:
         heterogeneity, heterogeneousness]