The Collaborative International Dictionary of English v.0.48:

Obsequiousness \Ob*se"qui*ous*ness\, n.
   The quality or state of being obsequious. --South.
   [1913 Webster]

WordNet (r) 3.0 (2006):

obsequiousness
    n 1: abject or cringing submissiveness [syn: obsequiousness,
         servility, subservience]