| Solution | Length | |
|---|---|---|
| 3 letters | ||
| set | 3 | |
| 4 letters | ||
| pest | 4 | |
| hard | 4 | |
| rock | 4 | |
| ruby | 4 | |
| 5 letters | ||
| rigid | 5 | |
| stiff | 5 | |
| stern | 5 | |
| rocky | 5 | |
| stony | 5 | |
| stone | 5 | |
| tough | 5 | |
| steel | 5 | |
| 6 letters | ||
| steely | 6 | |
| 7 letters | ||
| unmoved | 7 | |
| deadset | 7 | |
| 8 letters | ||
| rigorous | 8 | |
| resolute | 8 | |
| emphatic | 8 | |
| standpat | 8 | |
| ungiving | 8 | |
| stubborn | 8 | |
| sapphire | 8 | |
| 9 letters | ||
| well-made | 9 | |
| tenacious | 9 | |
| steadfast | 9 | |
| unpliable | 9 | |
| unbending | 9 | |
| unmovable | 9 | |
| 10 letters | ||
| well-built | 10 | |
| stationary | 10 | |
| IRONWILLED | 10 | |
| UNYIELDING | 10 | |
| relentless | 10 | |
| UNAFFECTED | 10 | |
| 11 letters | ||
| unrelenting | 11 | |
| unalterable | 11 | |
| 12 letters | ||
| UNCHANGEABLE | 12 | |
| recalcitrant | 12 | |
| 13 letters | ||
| well-grounded | 13 | |
| single-minded | 13 | |
| 14 letters | ||
| UNCOMPROMISING | 14 | |