| obtuse(adjective, dull, simple, silly, foolish) |
| scatterbrained |
| short-sighted(adjective, weak, simple, silly, foolish) |
| simple-minded(adjective, silly, foolish, stupid, green) |
| thick-witted(adjective, foolish, stupid, crazy, insane) |
| thickheaded |
| vacant(adjective, imbecility folly) |
| wild |
| zany(adjective, weak, simple, knowledge, ability) |
| backward(adjective, silly, foolish, stupid, vague) |
| bats in the belfry(expression, idiom, silly, foolish, mad) |
| benighted |
| birdbrained(adjective, silly, foolish, stupid, crazy) |
| bonkers(adjective, simple, silly, foolish, crazy) |
| cockamamy(silly, foolish, thoughtless, unwise, unintelligent) |
| crack-brained |
| crazed(adjective, wild, silly, foolish, stupid) |
| credulous(adjective, silly, stupid, green, fat) |
| dazed(dull, unintelligent, witless) |
| dense(adjective, dull, simple, slow, silly) |