Synonyms of harebrained

1 Syllable
rash, wild
2 Syllables
wacky, loony, flighty, giddy, heedless, loopy, tomfool, scatty, sillier, skittish, witless, nutty, flightier, crazy, silly, dingdong, nuttiest, dizzy, absurd, madcap, dippy, potty, silliest, nuttier, barmy, ditzy, foolish, pottier, swimmy, flightiest, mindless, reckless
3 Syllables
lightheaded, foolhardy, half-baked, bizarre, light-minded, nonserious, inanest, inane, foolheaded, squirrelly, unstable, softheaded, idiotic, frivolous, birdbrained, unsteady, careless, changeable
4 Syllables
agitable, preposterous, precipitant, cockamamy, addlebrained, unsensible, muddleheaded, alarmable, addleheaded, rattlebrained, asinine, uncareful, addlepated, imbecilic, empty-headed, featherbrained, ridiculous, bedlamite, scatterbrained
5 Syllables
inadvisable, ill-considered, irresponsible, unconsidered, unbelievable
7 Syllables
overventuresome