25B6; adjective
a hare-brained scheme : ILL-JUDGED, rash, foolish, foolhardy, reckless, madcap, wild, silly, stupid, ridiculous, absurd, idiotic, asinine, imprudent, impracticable, unworkable, unrealistic, unconsidered, half-baked, ill-thought-out, ill-advised, ill-conceived; informal crackpot, crackbrained, cock-eyed, crazy; Brit. informal daft, barmy.
a hare-brained young girl : FOOLISH, silly, idiotic, unintelligent, empty-headed, scatterbrained, feather-brained, birdbrained, pea-brained, brainless, giddy; informal dippy, dizzy, dopey, dotty, airheaded.
sensible, intelligent.