| Answer | Crossword Clue |
|---|---|
| unrepeatable | Not able to be done or made again |
| impossible | Not able to occur, exist, or be done |
| unrealizable | Not able to be achieved or made to happen |
| unbridgeable | (of a gap or difference) Not able to be bridged or made less significant |
| stealthiest | Behaving, done, or made in a cautious and surreptitious manner, so as not to be seen or heard |
| stealthy | Behaving, done, or made in a cautious and surreptitious manner, so as not to be seen or heard |
| stealthier | Behaving, done, or made in a cautious and surreptitious manner, so as not to be seen or heard |
