| stubborn(adjective, characteristic, quality, mean, strong) |
| tough(adjective, mean, clear, strong, hard) |
| uncompromising(adjective, mean, clear, hard, secure) |
| obdurate(adjective, strong, hard, secure, tough) |
| hard(adjective, mean, strong, tough, severe) |
| rigid(adjective, mean, strong, hard, tough) |
| inflexible(adjective, mean, strong, hard, secure) |
| severe(adjective, clear, strong, hard, tough) |
| resolute(adjective, determined, obstinate, uncompromising, unshakeable) |
| cruel(adjective, strong, hard, tough, severe) |
| difficult(adjective, hard, evil, rough, nasty) |
| nasty(adjective, hard, severe, rough, difficult) |
| rough(adjective, strong, hard, tough, severe) |
| rugged(adjective, strong, hard, tough, severe) |
| serious(adjective, strong, hard, tough, severe) |
| disturbing(adjective, hard, severe, difficult, complex) |
| intransigent(adjective, determined, resolute, obstinate, uncompromising) |
| obstinate(adjective, mean, hard, tough, rough) |
| sheer(adjective, hard, difficult, complex) |
| tight(adjective, hard, severe, difficult, complex) |