The Collaborative International Dictionary of English v.0.48:

Flibbertigibbet \Flib"ber*ti*gib`bet\, n.
   An imp. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flibbertigibbet
    n 1: a female fool [syn: flibbertigibbet, foolish woman]