Definition: something foolish or worthless
Flummadiddle is the sort of word that rolls nicely off the tongue, and even if people with whom you use the word don’t quite know what it means the conversation will be the richer for its presence. It has gone through a number of meanings and spellings since it first began being used in the early 19th century, with the earliest use apparently referring to a frill or fringe, as found on a dress.
… looking down, found I had disarrayed my fair partner of lots of roses, and two yards of flounce or flummediddle, which skirted the lower part of her dress.
— Ichabod, Boston Lyceum, March 1827
My stature is neither of predominating height, or insignificant brevity, and having observed that a redundance of ‘flemmediddle’ (as it is now called) is tolerable only on a lady of the first dimensions, and that a dress for the street without any addition of ornament looks rather a la Cinderella, or like a morning habiliment, a neat, appropriate trimming will be visible upon whatever I may wear, of my own work, (what a sneer, Miss Araminta! sneers do not become ladies, gentlemen may sneer as much as they please,)….
— Boston Spectator and Ladies’ Album, 21 Apr. 1827
Following its sartorial beginnings, flummadiddle began to be employed in other fashions; it comes up as a single-word headline for an article in a Massachusetts newspaper, The Salem Gazette, in 1829, without any apparent relation to the text of the article (which is about a walking stick); perhaps the editors of that paper simply liked the way the word looked.
By the middle of the 19th century flummadiddle was used variously as a verb or as an interjection:
L. (Jumping up.) Jupiter! thunder! a tete-a-tete with a vengeance! O, you etarnal varmint of a bat—I’ll show you how to flumadiddle around me!
— Spy-Glass, July 1840
O folly, fudge, and flummadiddle! We shall wait and see what next.
— Milwaukee Daily Sentinel, 18 Aug. 1848
In the 1840s it settled down a bit, and began to see service in the role that it was obviously born to play, which is as a synonym for fiddle-faddle, folderol, or flapdoodle.
The threat about retaining all Mexico is mere flummadiddle, of course.
— Boston Daily Bee, 8 Oct. 1846