crackbrained

having or showing a very abnormal or sick state of mind had the crackbrained idea that he was receiving radio signals from outer space Synonyms balmy, barmy [chiefly British], bats, batty, bedlam, bonkers, brainsick, bughouse [slang], certifiable, insane, cracked, crackers, crackpot, cranky [dialect], crazed, crazy, cuckoo, daffy, daft, demented, deranged, fruity [slang], gaga, haywire, kooky (also kookie), loco [slang], loony (also looney), loony tunes (or looney tunes), lunatic, mad, maniacal (also maniac), mental, meshuga (or meshugge also meshugah or meshuggah), moonstruck, non compos mentis, nuts, nutty, psycho, psychotic, scatty [chiefly British], screwy, unbalanced, unhinged, unsound, wacko (also whacko), wacky (also whacky), wud [chiefly Scottish]Related Words dotty, fey, loopy, off, potty [chiefly British], teched (or tetched), touched; aberrant, delirious, delusional, delusionary, disordered, disturbed, neurotic, obsessive-compulsive, paranoiac (also paranoic), paranoid (also paranoidal), schizoid, schizophrenic, sociopathic; eccentric, odd, oddball, pixilated (also pixillated), queer, strange; foolish, senseless, witless; irrational, unreasonable; amok (or amuck), ape, ballistic, bananas, berserk, nuclear; depressed; distracted, distraught, frantic, frenzied, haywire, hysterical (also hysteric), raving, wigged-out; fixated, monomaniac, monomaniacal, obsessedNear Antonyms clear, lucid, rational, reasonable; judicious, sensible, wise; healthy, normal, well-adjusted; unneuroticAntonyms balanced, compos mentis, sane, sound, uncrazy