| dyed-in-the-wool(adjective, hard, severe, harsh) |
| evident(certain, unquestionable, indisputable, unassailable) |
| inarguable(certain, unquestionable, indisputable, unassailable) |
| indubitable(certain, unquestionable, indisputable, unassailable) |
| invincible(certain, unquestionable, indisputable, unassailable) |
| irrebuttable(certain, unquestionable, indisputable, unassailable) |
| irresistible(certain, unquestionable, indisputable, unassailable) |
| nof ifs ands or buts(expression, certain, unquestionable, indisputable) |
| obvious(certain, unquestionable, indisputable, unassailable) |
| odds-on(certain, unquestionable, indisputable, unassailable) |
| positive(certain, unquestionable, indisputable, unassailable) |
| proven(certain, unquestionable, indisputable, unassailable) |
| resolute(adjective, hard, firm, determined) |
| steadfast(adjective, hard, firm, determined) |
| steely(adjective, hard, stiff, inflexible) |
| unanswerable(certain, unquestionable, indisputable, unassailable) |
| unimpeachable(certain, unquestionable, indisputable, unassailable) |