hare-brained

adjective

1 a hare-brained scheme:

ill-judged, rash, foolish, foolhardy, reckless, madcap, wild, silly, stupid, ridiculous, preposterous, absurd, idiotic, asinine, imprudent, impracticable, unworkable, unrealistic, unconsidered, half-baked, ill-thought-out, ill-advised, ill-conceived;

informal crackpot, crackbrained, cock-eyed, crazy;

British, informal daft, barmy.

▷antonyms sensible.

2 a hare-brained youngster:

foolish, silly, idiotic, unintelligent, empty-headed, scatterbrained, feather-brained, birdbrained, pea-brained, brainless, giddy;

informal dippy, dizzy, dopey, airheaded;

British, informal dappy, dotty.

▷antonyms intelligent.

hare-brained Oxford Dictionary of English