harebrained
[adjective]
Synonyms: giddy, dizzy, empty-headed, featherbrained, flighty, frivolous, rattlebrained, scatterbrained, silly, skittish, foolish, absurd, balmy, crazy, insane, loony, potty, preposterous, wacky

[TahlilGaran] English Synonym Dictionary ▲

harebrained /ˈheə.breɪnd/ US /ˈher-/
adjective
(of plans or people) not practical; foolish:
That sounds like another of his harebrained schemes!

[TahlilGaran] Advanced Learner's Dictionary ▲

harebrained
adj. Thoughtless; foolish.
Most of the harebrained things Ed does may be attributable to his youth and lack of experience.

[TahlilGaran] English Idioms Dictionary ▲