| dumb(adjective, dull, slow, silly, foolish) |
| effortless(noun, adjective, clear, light, weak) |
| frank(adjective, honest, plain, natural, straightforward) |
| homely(adjective, soft, plain, informal, relaxed) |
| lucid(adjective, quality, clear, easy, sharp) |
| soft(adjective, light, weak, easy, gentle) |
| brainless(adjective, characteristic, dull, weak, slow) |
| chaste(adjective, quiet, hard, soft, severe) |
| everyday(adjective, mean, poor, plain, informal) |
| fundamental(adjective, top, pure, straightforward, whole) |
| guileless(adjective, honest, plain, pure, natural) |
| informal(adjective, easy, plain, ordinary, familiar) |
| intelligible(adjective, quality, clear, easy, sharp) |
| open(adjective, clear, easy, flat, honest) |
| single(adjective, complete, honest, plain, pure) |
| unintelligent(adjective, dull, weak, slight, slow) |
| unostentatious(adjective, soft, honest, plain, informal) |
| bald(adjective, direct, honest, plain, cold) |
| feeble-minded(adjective, dull, ability, slow, offensive) |
| ignorant(adjective, characteristic, dull, open, slight) |