The Collaborative International Dictionary
featherbrained \feath"er*brained\, feather-brained \feath"er-brained\, a. Giddy; frivolous; lacking seriousness; given to frivolity; feather-headed. [Colloq.]
Syn: airheaded, dizzy, empty-headed, giddy, lightheaded, light-headed, silly.
Wiktionary
a. foolish, scatterbrained alt. foolish, scatterbrained
Usage examples of "feather-brained".
I've known hard women show soft, and soft women turn harpy, but blowed if I remember another who was at such extremes, a giggling feather-brained romp and a practised professional slayer.
Both Walkinshaw and Jack were perfectly at home with the mathematics of navigation and it was difficult for either to understand how very deeply ignorant it was possible for the young and feather-brained to be, particularly those young men who had spent most of their school-time ashore learning Latin and in some cases Greek and even a little Hebrew - possibly some French.
I used to think it was because you were a featherbrained flyboy-oh, courageous and daring and all the rest of it, but essentially feather-brained, too.
He had allowed himself to be drawn into indiscretions, to appear as one of the feather-brained crackpots for whom Marsden must have so much contempt.