| obsessive(adjective, fervent, persistent, obstinate, zealous) |
| perseverant |
| recalcitrant(adjective, tough, firm, persistent, obstinate) |
| refractory(adjective, tough, firm, persistent, obstinate) |
| stable(adjective, firm, solid, fixed, resolute) |
| stiff(adjective, tough, firm, harsh, cruel) |
| uncompliant(adjective, tough, firm, unreasonable, grim) |
| unconquerable(adjective, persistent, obstinate, insistent, dogged) |
| undaunted |
| unrelenting(adjective, tough, firm, harsh, cruel) |
| unruly(adjective, fervent, persistent, obstinate, zealous) |
| untiring |
| absorbed |
| artless(adjective, resolute) |
| assiduous |
| bent(adjective, intense, deliberate, determined, serious) |
| bloody-minded(adjective, persistent, obstinate, insistent, dogged) |
| cantankerous(tough, firm, persistent, obstinate, stubborn) |
| committed(adjective, keen, enthusiastic, resolute, persistent) |
| contrary(adjective, persistent, obstinate, insistent, dogged) |