The Collaborative International Dictionary of English v.0.48:

Splendiferous \Splen*dif"er*ous\, a.
   Splendor-bearing; splendid. --Bale (1538). "A splendiferous
   woman." --Haliburton. [Now used humorously.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

splendiferous
    adj 1: having great beauty and splendor; "a glorious spring
           morning"; "a glorious sunset"; "splendid costumes"; "a
           kind of splendiferous native simplicity" [syn:
           glorious, resplendent, splendid, splendiferous]

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "splendiferous":
   Babylonian, Corinthian, awe-inspiring, awful, barbaric, dazzling,
   deluxe, divine, elaborate, elegant, exquisite, extravagant, fancy,
   fine, gilt-edged, glorious, golden, gorgeous, grand, grandiose,
   heavenly, immense, imposing, impressive, luxurious, magnificent,
   majestic, marvelous, noble, palatial, plush, posh, princely, proud,
   rattling, resplendent, ripping, ritzy, screaming, sensational,
   smashing, splendacious, splendid, splendorous, stately, sterling,
   sublime, sumptuous, super, superb, supereminent, superexcellent,
   superfancy, superfine, swank, swanky, swell, terrific, tremendous,
   walloping, wonderful