| unswerving(adjective, strong, tough, firm, intense) |
| unsympathetic(adjective, animal, mean, hard, severe) |
| bound(adjective, strong, tough, firm, cruel) |
| demanding(adjective, severe, difficult, persistent, obstinate) |
| diligent(adjective, resolute) |
| everlasting(adjective, continue, steady, persistent, constant) |
| faithful(adjective, strong, firm, intense, determined) |
| habitual(adjective, persistent, continuous, endless, continual) |
| headstrong(adjective, strong, tough, cold, determined) |
| interminable(adjective, continue, determined, steady, persistent) |
| lasting(adjective, persistent, constant, continuous, endless) |
| loyal(adjective, strong, firm, intense, determined) |
| mortal(adjective, mean, severe, harsh, cruel) |
| ongoing(adjective, continue) |
| oppressive(adjective, severe, pure, absolute, severity) |
| pat(adjective, determined, resolute, obstinate, uncompromising) |
| regular(adjective, steady, persistent, constant, continuous) |
| stony-hearted(adjective, cold, cruel, unfeeling, unsympathetic) |
| strong-willed(adjective, determined, resolution, resolute, uncompromising) |
| unending(adjective, continue, steady, persistent, constant) |