| revengeful(adjective, mean, evil, nasty, harsh) |
| savage(adjective, animal, mean, hard, tough) |
| severe(adjective, appearance, mean, strong, hard) |
| tough(adjective, mean, strong, hard, firm) |
| unflinching(adjective, mean, severe, harsh, cruel) |
| unmerciful(adjective, mean, hard, tough, severe) |
| brassbound(adjective, resist, determined, resolute, persistent) |
| die-hard(adjective, resist, determined, resolute, persistent) |
| ferocious(adjective, animal, mean, evil, nasty) |
| stony(adjective, mean, hard, harsh, cold) |
| unbendable(adjective, resist, determined, resolute, persistent) |
| unchangeable(adjective, hard, resolute, rigid, inflexible) |
| unsympathetic(adjective, animal, mean, hard, severe) |
| vengeful(adjective, mean, severe, evil, nasty) |
| irreconcilable(adjective, hostile, conflicting) |
| bullheaded(adjective, strong, hard, tough, firm) |
| callous(adjective, mean, hard, severe, evil) |
| deadly |
| headstrong(adjective, determined, resolute, uncompromising, unshakeable) |
| mulish(adjective, mean, strong, hard, tough) |