| unstoppable(adjective, harsh, cruel, determined, fierce) |
| adamant(adjective, strong, hard, tough, harsh) |
| astringent(adjective, strong, hard, tough, severe) |
| austere(adjective, strong, hard, tough, severe) |
| authoritarian(adjective, strong, hard, tough, severe) |
| bitter(adjective, strong, hard, tough, severe) |
| bound(adjective, harsh, cruel, determined, fierce) |
| bound and determined(expression, adjective, idiom, harsh, cruel) |
| bullheaded(adjective, strong, hard, tough, severe) |
| by the book(expression, adjective, idiom, strong, hard) |
| dead set on(expression, adjective, idiom, harsh, cruel) |
| determined(adjective, harsh, cruel, fierce, persistent) |
| disciplinary(adjective, strong, hard, tough, severe) |
| dogged(adjective, harsh, cruel, determined, fierce) |
| dyed-in-the-wool(adjective, strong, hard, tough, severe) |
| ferocious(adjective, harsh, cruel, determined, fierce) |
| fierce(adjective, harsh, cruel, determined, persistent) |
| flinty(adjective, strong, hard, tough, severe) |
| forbidding(adjective, strong, hard, tough, severe) |
| frowning(adjective, strong, hard, tough, severe) |