| indistinguishable(adjective, weak, obscure, dark, vague) |
| lightless(adjective, dull, obscure, dark, gloomy) |
| mist(verb, cover, clear, obscure, hide) |
| shaded(adjective, dull, quiet, cool, gentle) |
| sombre(adjective, dull, obscure, flat, dark) |
| sunless(adjective, dull, dark, gloomy, mood) |
| tarnish(verb, dull, reduce, diminish, lower) |
| thick-witted(adjective, dull, stupid) |
| blacken(verb, dull, cover, obscure, protect) |
| cheerless(adjective, blue, sad, depression, woe) |
| half-witted(adjective, dull, simple, stupid, limited) |
| imperceptible(adjective, dull, weak, soft, gentle) |
| indeterminate(adjective, weak, obscure, rough, dark) |
| mat(adjective, light, dark, gloomy, murky) |
| shadow(verb, cover, clear, obscure, confuse) |
| sluggish(adjective, dull, simple, slow, unintelligent) |
| slur |
| stolid(adjective, dull, simple, slow, unintelligent) |
| thickheaded |
| umbrageous(adjective, cool, dark, shady, indefinite) |