| depurative |
| determined(adjective, strong, hard, tough) |
| disciplinary(adjective, strong, hard, tough, sturdy) |
| dyed-in-the-wool(adjective, strong, hard, tough, sturdy) |
| ferric acid(expression, idiom) |
| firm(adjective, strong, hard, tough, sturdy) |
| flinty(adjective, strong, hard, tough, sturdy) |
| forbidding(adjective, strong, hard, tough, sturdy) |
| frowning(adjective, strong, hard, tough, sturdy) |
| grim(adjective, strong, hard, tough, sturdy) |
| hang-tough(adjective, strong, hard, tough, sturdy) |
| hard(adjective, strong, tough, sturdy, rigid) |
| hard-boiled(adjective, strong, hard, tough, sturdy) |
| hard-core(adjective, strong, hard, tough, sturdy) |
| hard-line(adjective, strong, hard, tough, sturdy) |
| hard-nosed(adjective, strong, hard, tough, sturdy) |
| hard-shell(adjective, strong, hard, tough, sturdy) |
| hard as nails(expression, adjective, idiom, strong, hard) |
| hardheaded(adjective, strong, hard, tough, sturdy) |
| harsh(adjective, strong, hard, tough, sturdy) |