| remorseless(adjective, resist, determined, resolute, persistent) |
| unbendable(adjective, resist, determined, resolute, persistent) |
| unforgiving(adjective, determined, resolute, uncompromising, unshakeable) |
| mulish(adjective, strong, hard, tough, firm) |
| pigheaded(adjective, tough, determined, resolute, stubborn) |
| stiff-necked(adjective, strong, hard, tough, firm) |
| business-minded |
| hard-nosed(adjective, strong, hard, tough, determined) |
| hardened(adjective, strong, firm, determined, stiff) |
| headstrong(adjective, determined, resolute, uncompromising, unshakeable) |
| opinionated(adjective, determined, resolute, stubborn, uncompromising) |
| steadfast(adjective, tough, firm, determined, resolute) |
| strong(adjective, set, hard, strength, tough) |
| sturdy(adjective, strong, hard, strength, tough) |
| unappeasable(adjective, determined, resolute, uncompromising, unshakeable) |
| dogged(adjective, tough, firm, determined, resolute) |
| insistent(adjective, determined, resolute, uncompromising, unshakeable) |
| ossified(adjective, determined, resolute, uncompromising, unshakeable) |
| rigorous(adjective, set, strong, hard, tough) |
| unshakable(adjective, determined, resolute, uncompromising, unshakeable) |