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):

sumptuous
    adj 1: rich and superior in quality; "a princely sum"; "gilded
           dining rooms" [syn: deluxe, gilded, grand,
           luxurious, opulent, princely, sumptuous]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "sumptuous":
   Babylonian, Corinthian, awe-inspiring, awful, barbaric, bask,
   costly, dazzling, dear, dear-bought, deluxe, elaborate, elegant,
   exorbitant, expensive, extravagant, fancy, fine, glorious,
   gorgeous, grand, grandiose, high, high-priced, imposing,
   impressive, insolate, lavish, luscious, lush, luxuriant, luxurious,
   magnificent, majestic, noble, not affordable, of great cost,
   opulent, palatial, plush, posh, premium, pricey, princely, proud,
   regal, resplendent, rich, ritzy, royal, showy, splendacious,
   splendid, splendiferous, stately, steep, stiff, sun, sun-dry,
   sunbathe, sunburn, superb, superfancy, superfine, swank, swanky,
   swell, tan, top, unpayable