harebrained
adjective
1 a harebrained 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.