| inconceivable(unbelievable, unthinkable, unimaginable) |
| incredible(extraordinary, strange, unbelievable, implausible, unthinkable) |
| insane(adjective, foolish, fantastic, unrealistic) |
| irresponsible(adjective, foolish, fantastic, unrealistic) |
| loony(adjective, foolish, fantastic, unrealistic) |
| ludicrous(adjective, foolish, fantastic, unrealistic) |
| mind-blowing(unbelievable, unthinkable, unimaginable) |
| nonsensical(adjective, foolish, fantastic, unrealistic) |
| odd(adjective, foolish, fantastic, unrealistic) |
| out of all reason(expression, adjective, idiom, strange, foolish) |
| outrageous(adjective, foolish, fantastic, unrealistic) |
| peculiar(adjective, foolish, fantastic, unrealistic) |
| preposterous(adjective, foolish, fantastic, unrealistic) |
| puerile(adjective, foolish, fantastic, unrealistic) |
| quixotic(adjective, foolish, fantastic, unrealistic) |
| ridiculous(adjective, foolish, fantastic, unrealistic) |
| senseless(adjective, foolish, fantastic, unrealistic) |
| short-sighted(adjective, foolish, fantastic, unrealistic) |
| silly(adjective, foolish, fantastic, unrealistic) |
| thin(extraordinary, strange, unbelievable, implausible, unthinkable) |