| sturdy(adjective, strong, hard, tough, firm) |
| unalterable(adjective, determined, steady, definite, fixed) |
| unconquerable(adjective, characteristic, resistance, persistence, stubbornness) |
| unreasonable(adjective, characteristic, quality, tough, firm) |
| untiring(adjective, characteristic, persistence, stubbornness) |
| wrongheaded(adjective, characteristic, negative, hostile, different) |
| bovine(adjective, determined, resolute, obstinate, uncompromising) |
| courageous(adjective, characteristic, resolute, persistence, stubbornness) |
| cussed(adjective, characteristic, quality, tough, firm) |
| daring(adjective, characteristic, persistence, stubbornness, defiant) |
| dauntless(adjective, characteristic, resolute, persistence, stubbornness) |
| difficult to handle(expression, adjective, characteristic, quality, refusal) |
| difficult to overcome(expression, adjective, characteristic, quality, refusal) |
| difficult to treat(expression, adjective, characteristic, quality, refusal) |
| fixed in opinion(expression, adjective, characteristic, quality, refusal) |
| fixed in purpose(expression, adjective, characteristic, quality, refusal) |
| hard-headed(adjective, characteristic, persistence, stubbornness) |
| heady(adjective, characteristic, determined, fixed, persistence) |
| immutable(adjective, firm, steady, fixed, rigid) |
| indurate(adjective, mean, hard, determined, resolute) |