commonly spelled flibbertigibbet
1) A capricious and unreliable person.
2) a flighty or whimsical person, usually a young female.
3) Historically: a name for a fiend, devil, puck or sprite.
4) Mythology: The name of a particularly obnoxious
apprentice to the Wayland (Weland) smith who was
so irritated by his apprentice threw him down a hill where he was changed into a stone.
In "The sound of Music" Maria is called a flibbertygibbet by the Mother Superior because Maria is out roaming aroundthe hills rather than staying in the convent and behaving as a novice should.
Once used by my grandmother - told to me when I could not make up my mind - "A polite but funny Insult"
You are a flibbertyjibbit. You get really excited about something, throw yourself into it for a week, and then forget all about it. You buy things from QVC. Your basement is crammed with toys you no longer play with -- shotguns, the Duroflex, self-help cassettes. You don't have a significant other because you are incapable of committing, which is just as well, because you're selfish and lousy company.