| erroneous(false, ill, insane, unhealthy, frail) |
| error-prone(adjective, unreliable, insecure, treacherous, incalculable) |
| evil(injurious, damaging, destructive) |
| fairweather(adjective, unreliable, insecure, treacherous, incalculable) |
| fallacious(false, ill, insane, unhealthy, frail) |
| fallible(adjective, unreliable, insecure, treacherous, incalculable) |
| false(adjective, unstable, dishonest, ill, sick) |
| fast and loose(adjective, unreliable, insecure, treacherous, incalculable) |
| faulty(false, ill, insane, unhealthy, frail) |
| flawed(false, unstable, ill, shaky, insane) |
| fluctuant(unstable, shaky, vulnerable, dangerous, unsteady) |
| fly by night(adjective, unreliable, insecure, treacherous, incalculable) |
| foolish |
| formidable(adjective, dangerous) |
| fragile(false, unstable, ill, shaky, insane) |
| frail(unstable, ill, unhealthy, vulnerable, dangerous) |
| frantic(foolish, fantastic) |
| frenetic(foolish, fantastic) |
| giddy |
| going for broke(expression, idiom, delicate, uncertain, unsound) |