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". In the sense of "delicious" – from 1881.
scrumptious (comparative more scrumptious, superlative most scrumptious)
- (informal) Delicious; delectable.
- What a scrumptious treat!
- (informal, obsolete) Picky; fastidious.
- ^ The slang dictionary: or, The vulgar words, street phrases, and "fast" expressions of high and low society. Many with their etymology, and a few with their history traced. J.C. Hotten, 1864. (Google books: page 223 contains "scrumptious")