| witless(adjective, foolish, crazy, mad, odd) |
| zany(adjective, weak, simple, knowledge, ability) |
| bedlamite(noun, adjective, person, keen, warm) |
| dumb(adjective, foolish, impractical, unintelligent, half-baked) |
| haywire |
| irrational(adjective, weak, simple, careless, wild) |
| mentally ill(expression, adjective, idiom, sane, unwell) |
| non compos mentis(noun, expression, adjective, idiom, law) |
| tomfool(adjective, knowledge, ability, foolish) |
| unhinged(adjective, silly, foolish, stupid, unwise) |
| cockeyed(adjective, knowledge, ability, informal, silly) |
| eccentric(noun, adjective, wild, strange, silly) |
| inane(adjective, foolish, stupid, fantastic, senseless) |
| loon(noun, slang, informal, sick, wise) |
| ludicrous(adjective, light, foolish, stupid, crazy) |
| nutter(noun, slang, sick, mad person) |
| round the bend(expression, adjective, idiom, silly, foolish) |
| wild(adjective, wrong, strange, silly, foolish) |
| brainless(adjective, weak, simple, silly, foolish) |
| certifiable |