| stale(adjective, dull, weak, simple, flat) |
| stiff(adjective, dull, slow, heavy, sluggish) |
| stodgy |
| stuffy |
| stupefied(adjective, dull, stupid, idle, weary) |
| stupid(adjective, dull, flat, ordinary, dry) |
| supine(adjective, dull, weak, easy, slow) |
| tame(adjective, dull, weak, simple, flat) |
| tired(adjective, dull, flat, slow, indifferent) |
| treadmill(adjective, dull, boring, routine, tedious) |
| tripe(adjective, stupid, ordinary, commonplace, bland) |
| trite(adjective, dull, simple, flat, plain) |
| unconcerned(adjective, calm, dull, weak, easy) |
| uneventful(adjective, dull, quiet, simple, flat) |
| uninspiring(adjective, dull, weak, simple, flat) |
| uninterested(adjective, dull, weak, easy, slow) |
| unvarying |
| vanilla(adjective, dull, weak, smooth, simple) |
| weak(adjective, dull, smooth, pleasant, easy) |
| wimpy(adjective, dull, weak, smooth, pleasant) |