| ferocious(adjective, harsh, cruel, determined, fierce) |
| fierce(adjective, harsh, cruel, determined, persistent) |
| forceful(adjective, severe, determined, vigorous, stiff) |
| go for broke(expression, adjective, idiom, harsh, cruel) |
| grim(adjective, harsh, cruel, determined, fierce) |
| hang-tough(adjective, harsh, cruel, determined, fierce) |
| hang in(expression, adjective, harsh, cruel, determined) |
| hang tough(expression, adjective, strong, certain, definite) |
| hanging tough(expression, adjective, firm, determined, vigorous) |
| hard(adjective, severe, harsh, cruel, determined) |
| hard-nosed(adjective, secure, severe, steady, fixed) |
| harsh(adjective, severe, cruel, determined, fierce) |
| headstrong(adjective, firm, determined, fixed, resolute) |
| immovable(adjective, secure, cruel, determined, usual) |
| immutable |
| implacable(adjective, harsh, cruel, determined, fierce) |
| indefatigable(adjective, untiring) |
| indomitable(adjective, determined, vigorous, fixed, resolute) |
| industrious |
| inexhaustible |