D defs.my
Entry 1 sense Webster, 1913

crackbrained

/(-brānd`)/ · IPA
01 a. Having an impaired intellect; whimsical; extremely foolish; crazy; as, crackbrained notions.
  1. 1.
    Having an impaired intellect; whimsical; extremely foolish; crazy; as, crackbrained notions.
Syn. idiotic.