| single-minded(adjective, characteristic, quality, tough, firm) |
| strong(adjective, hard, tough, firm, violent) |
| remorseless(adjective, characteristic, quality, resist, cruel) |
| unflagging(adjective, characteristic, persistence, stubbornness, tenacious) |
| hanging tough(expression, adjective, mean, hard, determined) |
| indomitable(adjective, strong, hard, tough, difficult) |
| staunch(adjective, characteristic, quality, strong, tough) |
| defiant(adjective, characteristic, unwilling, defiant) |
| doctrinaire(adjective, characteristic, persistence, stubbornness, opinionated) |
| indefatigable(adjective, characteristic, resolute, persistence, stubbornness) |
| tireless(adjective, characteristic, resolute, persistence, stubbornness) |
| bigoted(adjective, determined, resolute, fervent, inflexible) |
| bold(adjective, resolute, tenacious, defiant) |
| stern(adjective, appearance, hard, tough, rough) |
| cantankerous(adjective, characteristic, quality, tough, firm) |
| diligent(adjective, characteristic, resolute, persistence, stubbornness) |
| hidebound(adjective, determined, stiff, resolute, obstinate) |
| inelastic(adjective, determined, resolute, obstinate, uncompromising) |
| unswerving(adjective, strong, tough, firm, intense) |
| bulldogged(adjective, characteristic, persistence, stubbornness, tenacious) |