The Collaborative International Dictionary of English v.0.48:

Lavishness \Lav"ish*ness\, n.
   The quality or state of being lavish.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lavishness
    n 1: the quality possessed by something that is excessively
         expensive [syn: lavishness, luxury, sumptuosity,
         sumptuousness]
    2: excessive spending [syn: extravagance, prodigality,
       lavishness, highlife, high life]