| conventional(adjective, stupid, ordinary, commonplace, bland) |
| cornball(adjective, stupid, ordinary, commonplace, puny) |
| cornfed(adjective, stupid, ordinary, commonplace, puny) |
| corny(adjective, stupid, ordinary, commonplace, bland) |
| dead(adjective, dull, simple, flat, plain) |
| delicate(adjective, weak, thin, incompetent, frail) |
| dew point |
| diddly(noun, adjective, simple, flat, clean) |
| diminutive(weak, feeble, frail, tiny, measly) |
| distasteful(adjective, dull, weak, flat, boring) |
| dopey(dull, weak, low, thin, depressed) |
| douchebag(noun, characteristic, slang, swear) |
| draggy(adjective, dull, flat, low, sad) |
| dreary |
| dry(adjective, dull, simple, flat, clean) |
| duck |
| dud |
| dull as dishwater(expression, adjective, idiom, dull, weak) |
| enervated(dull, weak, low, thin, depressed) |
| ethereality(noun, unsubstantiality) |