| grisly(adjective, appearance, terrible, hopeless) |
| gruesome(adjective, appearance, terrible, hopeless) |
| hard-shell(adjective, strong, hard, tough, persistent) |
| hardened(adjective, hard, tough, harsh, determined) |
| immobile(adjective, intense, cruel, resolute, persistent) |
| indefatigable(adjective, resolute) |
| inhuman(adjective, mean, hard, tough, evil) |
| irreconcilable(adjective, hostile, conflicting) |
| narrow(adjective, intolerant, small-minded) |
| obligatory(adjective, obvious, expected, predictable, compulsion) |
| perverse(adjective, mean, hard, tough, violent) |
| recalcitrant(adjective, tough, firm, persistent, obstinate) |
| refractory(adjective, tough, firm, persistent, obstinate) |
| resistant(adjective, determined, resolute, obstinate, uncompromising) |
| self-willed(adjective, tough, firm, determined, resolute) |
| stringent(adjective, severe, harsh, cruel, determined) |
| strong-minded(adjective, resolution, resolute) |
| tyrannical(adjective, hard, tough, evil, nasty) |
| uncooperative(adjective, mean, hard, persistent, rigid) |
| unpitying(adjective, mean, severe, harsh, cruel) |