| incompliant(adjective, tough, firm, solid, resist) |
| pat(adjective, determined, resolute, obstinate, uncompromising) |
| stiff-necked(adjective, mean, strong, hard, tough) |
| contrary(adjective, determined, resolute, obstinate, stubborn) |
| die-hard(adjective, tough, moderate, resist, determined) |
| hardened(adjective, person, hard, tough, firm) |
| hardheaded(adjective, strong, hard, tough, cold) |
| immutable(adjective, set, hard, secure, rough) |
| invariable(adjective, smooth, solid, level, true) |
| staunch(adjective, strong, tough, flat, firm) |
| stringent(adjective, hard, severe, rough, difficult) |
| callous(adjective, person, hard, tough, rough) |
| opinionated(adjective, firm, determined, unreasonable, fixed) |
| perverse(adjective, mean, hard, firm, deliberate) |
| standing pat(adjective, determined, resolute, obstinate, uncompromising) |
| unforgiving(adjective, person, hard, rough, harsh) |
| unsympathetic(adjective, mean, hard, careless, indifferent) |
| brassbound(adjective, resist, determined, resolute, persistent) |
| bull-headed(adjective, determined, resolute, obstinate, stubborn) |
| flinty(adjective, strong, hard, tough, severe) |