| characterless |
| clean(adjective, simple, flat, plain, ordinary) |
| cliché-ridden(dull, hard, standard, old, sour) |
| cliche(dull, set, hard, flat, silly) |
| colloquial(adjective, simple, ordinary, familiar, natural) |
| colorless(adjective, dull, weak, simple, clean) |
| comformable(adjective, simple, ordinary, familiar, natural) |
| copybook |
| corn |
| cornball(adjective, dull, set, flat, silly) |
| current(adjective, simple, ordinary, familiar, natural) |
| customary(adjective, simple, ordinary, familiar, natural) |
| cut-and-dried |
| daily(adjective, simple, ordinary, familiar, natural) |
| diddly(adjective, simple, flat, clean, plain) |
| dim(adjective, dull, weak, ordinary, dead) |
| draggy(adjective, dull, weak, boring, dead) |
| drained(adjective, dull, set, flat, silly) |
| dry-as-dust |
| dull as dishwater(expression, adjective, idiom, dull, weak) |