| insubstantial(adjective, dull, body, strong, light) |
| flimsy(adjective, strong, light, weak, great) |
| weak(adjective, dull, strong, light, great) |
| fragile(adjective, strong, light, weak, slight) |
| frail(adjective, strong, light, weak, slight) |
| feeble(adjective, dull, strong, light, weak) |
| shaky(adjective, weak, slight, thin, delicate) |
| unsound(adjective, bad, strong, light, weak) |
| decrepit(adjective, strong, light, weak, slight) |
| delicate(adjective, strong, light, weak, slight) |
| infirm(adjective, strong, light, weak, slight) |
| rickety(adjective, weak, slight, weakness, thin) |
| unstable(adjective, weak, delicate, false) |
| unsteady(adjective, false, uncertain, unstable) |
| insecure(adjective, weak, delicate, false, unstable) |
| fallacious(bad, false, error, insane) |
| false(bad, light, weak, slight) |
| erroneous(bad, false, error, insane) |
| faint(adjective, dull, light, weak, soft) |
| illogical(adjective, false, sense, unstable) |