| opaque(adjective, hard, slow) |
| thick-witted(adjective, dull, ability, stupid) |
| cloddish(adjective, dull) |
| dopey(adjective, dull, slang, ability, slow) |
| ignorant(adjective, dull, simple, slow, silly) |
| witless(adjective, dull, simple, slow, careless) |
| boneheaded(adjective, simple, slow, stupid) |
| bovine(adjective, dull, careless, heavy, foolish) |
| foolish(adjective, dull, simple, careless, silly) |
| half ass |
| imperceptive(adjective, hard, obscure, difficult, slow) |
| lumpish(adjective, dull, heavy, stupid, vulgar) |
| sluggish(adjective, dull, simple, slow, stupid) |
| asinine(adjective, silly, foolish, stupid, vulgar) |
| backward(adjective, dull, simple, slow, silly) |
| crass(adjective, hard, indifferent, coarse, vulgar) |
| fatuous |
| heavy(adjective, dull, stupid, impassive, unresponsive) |
| imbecilic(adjective, dull, simple, slow, silly) |
| impassive(adjective, dull, hard, slow, stupid) |