Scrumptious
mid 19th century: of unknown origin.
wiktionary
Probably an alteration of sumptuous. First noted in 1836, and originally meant "picky, fastidious" or "stylish, splendid": for example, a 1864 dictionary of slang defines it as "nice, particular, beautiful". [1] In the sense of "delicious" – from 1881.
etymonline
scrumptious (adj.)
1833, American English, in countrified humor writing of "Major Jack Downing" of Maine (Seba Smith), "stylish, splendid, fine;" probably a colloquial alteration (intensification) of sumptuous. By late 19c. especially of food, "delicious, delightful," and it was noted 1890s and early 20c. as a vogue word among college girls (also as scrum, scrummy). Related: Scrumptiously; scrumptiousness.
OED (2nd edition, print) has scrumptious as probably identical with dialectal scrumptious "mean, stingy, close-fisted," and ultimately related to shrimp. The editors insist the sense transition "is not impossible," and they compare nice.
