The Collaborative International Dictionary of English v.0.48:

Scrumptious \Scrump"tious\, a.
   Nice; particular; fastidious; excellent; fine. [Slang]
   [1913 Webster]

WordNet (r) 3.0 (2006):

scrumptious
    adj 1: extremely pleasing to the sense of taste [syn:
           delectable, delicious, luscious, pleasant-
           tasting, scrumptious, toothsome, yummy]

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "scrumptious":
   OK, ace-high, adorable, agreeable, ambrosial, bad, bang-up, bonzer,
   boss, bully, but good, cool, corking, crackerjack, dainty, dandy,
   darling, delectable, delicate, delicious, delightful, ducky,
   exquisite, fab, fine and dandy, gear, good, good to eat,
   good-tasting, great, groovy, gustable, gusty, heavenly, heavy, hot,
   hunky-dory, jam-up, juicy, just dandy, keen, likable, luscious,
   lush, marvy, mean, neat, nectareous, nectarous, nice, nifty, nobby,
   of gourmet quality, okay, out of sight, palatable, peachy,
   peachy-keen, pleasing, ripping, rum, sapid, savorous, savory,
   slap-up, smashing, solid, something else, spiffing, spiffy,
   stunning, succulent, swell, tasty, toothsome, tough, wizard,
   yummy