1 a silly, scatterbrained, or garrulous person
2 (archaic) a gossip
This is how we will stay strong through this crisis. Why, just last night I entered my bathroom a mild-mannered person sliding quickly into madness and emerged a self-proclaimed flibbertigibbet with red hair and a weird husky voice modeled after Angelica, the second of Ryan's characters in the film. Is this what the public (my houseplants) wants? No. Is it what the public (my houseplants) needs? Absolutely. I am an altruistic flibbertigibbet and you're welcome. (R Eric Thomas, Finding Solace in Life's Absurdity and Terror in Joe Versus the Volcano, yahoonews, April 2020)
A flibbertigibbet in a Little Red Riding Hood raincoat, with a reckless habit of stepping out on to life’s busiest roads? (Kiran Sidhu, How my farmer friend Wilf gave me a new perspective, The Guardian, August 2021)
As blue chips turn into penny stocks, Wall Street seems less like a symbol of America's macho capitalism and more like that famous Jane Austen character Mrs. Bennet, a flibbertigibbet always anxious about getting richer and her 'poor nerves'. (Kiran Sidhu, Well-toned first lady brings style to her job, South Florida SunSentinel, March 2009)
All this responsibility at such an early age made her a bitchy flibbertigibbet. (Kurt Vonnegut, Slaughterhouse-Five)
1540s, 'chattering gossip, flighty woman,' probably a nonsense word meant to sound like fast talking; as the name of a devil or fiend it dates from c. 1600 (together with Frateretto, Hoberdidance, Tocobatto). OED lists 15 spellings and thinks flibbergib is the original. (Online Etymology Dictionary)
It's a fine word to throw out, in the appropriate circumstances, though there's a risk of tripping over all those syllables. That's no doubt why it has had so many spellings.
The original seems to have been recorded about 1450 as fleper-gebet, which may have been just an imitation of the sound of meaningless speech (babble and yadda-yadda-yadda have similar origins). It started out to mean a gossip or chattering person, but quickly seems to have taken on the idea of a flighty or frivolous woman. A century later it had become respectable enough for Bishop Latimer to use it in a sermon before King Edward VI, though he wrote it as flybbergybe.
The modern spelling is due to Shakespeare, who borrowed it from one of the 40 fiends listed in a book by Samuel Harsnet in 1603. In King Lear Edgar uses it for a demon or imp: "This is the foul fiend Flibbertigibbet... He gives the web and the pin, squints the eye, and makes the harelip; mildews the white wheat, and hurts the poor creature of earth".
There has been yet a third sense, taken from a character of Sir Walter Scott's in Kenilworth, for a mischievous and flighty small child. But despite Shakespeare and Scott, the most usual sense is still the original one. (World Wide Words)