| harsh(adjective, mean, strong, hard, tough) |
| incompliant(adjective, firm, resist, determined, resolute) |
| resolved(adjective, strong, severe, flat, firm) |
| set in stone(expression, adjective, idiom, mean, hard) |
| stiff-necked(adjective, mean, strong, hard, tough) |
| strict(adjective, strong, hard, tough, severe) |
| unswayable(adjective, determined, resolute, rigid, obstinate) |
| unswerving(adjective, direct, solid, determined, straight) |
| steady(adjective, strong, flat, firm, certain) |
| rigorous(adjective, strong, hard, tough, severe) |
| unchangeable(adjective, strong, flat, certain, determined) |
| unflinching(adjective, strong, flat, firm, harsh) |
| brassbound(adjective, resist, determined, resolute, persistent) |
| constant(adjective, strong, flat, firm, certain) |
| die-hard(adjective, resist, determined, resolute, persistent) |
| hanging tough(expression, adjective, mean, hard, determined) |
| headstrong(adjective, hard, tough, rough, harsh) |
| mulish(adjective, mean, strong, hard, tough) |
| pat(adjective, difficult, determined, resolute, obstinate) |
| perverse(adjective, mean, hard, tough, determined) |