| slow(adjective, dull, light, easy, ability) |
| thick(adjective, dull, slow, silly, foolish) |
| unalloyed(adjective, separate, complete, clean, total) |
| undecorated(adjective, plain, ordinary, modest, natural) |
| unmixed(adjective, separate, complete, clean, pure) |
| backward(adjective, dull, quiet, ability, slow) |
| blunt(adjective, clear, hard, severe, flat) |
| childish(adjective, pure, foolish, stupid, innocent) |
| commonplace(adjective, dull, mean, lower, poor) |
| credulous(adjective, pure, silly, stupid, intelligent) |
| doltish(adjective, dull, weak, slow, silly) |
| familiar(adjective, plain, informal, relaxed, common) |
| forthright(adjective, direct, honest, plain, natural) |
| gullible(adjective, dull, silly, foolish, stupid) |
| imbecile(noun, adjective, dull, ability, slow) |
| imbecilic(adjective, dull, weak, slow, silly) |
| indivisible(adjective, separate, pure, special, individual) |
| mindless(adjective, dull, slow, silly, foolish) |
| obtuse(adjective, dull, slow, silly, foolish) |
| prosaic(adjective, mean, gentle, poor, low) |