feather-brained

Nor did she like the atmosphere of the Whites and Rocca Marina for her feather-brained young sister.

If you have the selection, pick out some earnest person, and avoid the trifling, feather-brained class.

And we can be sure that he was considered feather-brained and anarchistic by his conservative tribesmen.

Surely there never did exist so volatile, light-spirited, feather-brained a race as these same Negro Blacks.

Of course, it was a feather-brained scheme from start to finish, and yet in a fashion it attracted her.