| harebrained(extraordinary, amazing, dubious, astonishing, incredible) |
| ill-advised(careless, stupid, unthinking, obtuse, unperceptive) |
| ill-considered(careless, stupid, unthinking, obtuse, unperceptive) |
| implausible(extraordinary, amazing, incredible) |
| impossible(extraordinary, amazing, incredible) |
| improbable(extraordinary, amazing, incredible) |
| inane(careless, silly, stupid, unthinking, unintelligent) |
| incogitable(extraordinary, amazing, dubious, astonishing, incredible) |
| incomprehensible(careless, stupid, unthinking, obtuse, unperceptive) |
| inconceivable(extraordinary, amazing, incredible) |
| incredible(extraordinary, amazing) |
| ineducable |
| inept(careless, stupid, unthinking, obtuse, unperceptive) |
| irrational(careless, stupid, unthinking, obtuse, unperceptive) |
| irreflective(careless, stupid, unthinking, obtuse, unperceptive) |
| klutzy |
| kooky(extraordinary, amazing, dubious, astonishing, incredible) |
| loony(careless, stupid, unthinking, obtuse, unperceptive) |
| lumpish |
| mentally defective(adjective, dull, simple, limited) |