foolish; flighty; scatterbrained.
empty-headed, flighty, harebrained, scatterbrained, silly, airheaded, scatty, daffy, dizzy, dopey, eccentric, empty, giddy, goofy, inane, dippy, kooky, absurd, asinine, barmy
Origin of rattlebrained
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for rattlebrained
Historical Examples of rattlebrained
Stop that bosh, you rattlebrained young ass, and come and take a farewell drink.