| blockheaded(adjective, foolish, impractical, half-baked, doomed) |
| crackpot(adjective, foolish, impractical, half-baked, doomed) |
| cuckoo(adjective, silly, foolish, unwise) |
| dizzy(adjective, scatterbrained, flighty) |
| dopey(adjective, dull, simple, silly, foolish) |
| dull(adjective, weak, simple, careless, silly) |
| flat(adjective, dull, stupid, lackluster) |
| flimsy(adjective, slight, poor, trivial, unimportance) |
| fruitless(adjective, dull, stupid, insignificant, useless) |
| hollow(adjective, slight, value, small, silly) |
| idle(adjective, unimportance) |
| insipid(adjective, dull, weak, soft, sweet) |
| sappy(adjective, soft, informal, silly, stupid) |
| shallow(adjective, slight, small, silly, stupid) |
| trifling(adjective, slight, poor, thin, false) |
| unoccupied(adjective, thoughtless) |
| useless(adjective, value, stupid, insignificant, unimportant) |
| weak(adjective, dull, thin, false, silly) |
| zany(adjective, silly, foolish, unwise) |
| batty(adjective, wild, silly, foolish, stupid) |