| nugatory |
| obsolete |
| otherworldly(wild, unreasonable, useless, absurd, abstract) |
| otiose |
| out-of-use(adjective, useless, unfit) |
| out of order(expression, idiom) |
| out of whack(expression, idiom) |
| pointless(adjective, impractical, hopeless, unusable) |
| precarious(adjective, unreliable, insecure, treacherous, incalculable) |
| pregnable(adjective, unreliable, insecure, treacherous, incalculable) |
| purposeless(adjective, impractical, hopeless, unusable) |
| questionable(adjective, unreliable, insecure, treacherous, incalculable) |
| quixotic(wild, unreasonable, useless, absurd, abstract) |
| romantic(wild, unreasonable, useless, absurd, abstract) |
| shaky(adjective, unreliable, insecure, treacherous, incalculable) |
| slippery(adjective, unreliable, insecure, treacherous, incalculable) |
| slow(adjective, useless, unfit) |
| speculative(wild, unreasonable, useless, absurd, abstract) |
| starry-eyed(wild, unreasonable, useless, absurd, abstract) |
| suss(adjective, unreliable, insecure, treacherous, incalculable) |