The Collaborative International Dictionary of English v.0.48:

Sumptuous \Sump"tu*ous\, a. [L. sumptuosus, fr. sumptus expanse,
   cost: cf. F. somptueux. See Sumptuary.]
   Involving large outlay or expense; costly; expensive; hence,
   luxurious; splendid; magnificient; as, a sumptuous house or
   table; sumptuous apparel.
   [1913 Webster]

         We are too magnificient and sumptuous in our tables and
         attendance.                              --Atterbury.
   [1913 Webster]

         She spoke, and turned her sumptuous head, with eyes
         Of shining expectation fixed on mine.    --Tennyson.
   [1913 Webster] -- Sump"tu*ous*ly, adv. --
   Sump"tu*ous*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sumptuousness
    n 1: wealth as evidenced by sumptuous living [syn: luxury,
         luxuriousness, opulence, sumptuousness]
    2: the quality possessed by something that is excessively
       expensive [syn: lavishness, luxury, sumptuosity,
       sumptuousness]