| contumacious(adjective, persistent, obstinate, insistent, dogged) |
| cruel(adjective, strong, hard, tough, severe) |
| deep-seated(adjective, continue, confirmed) |
| defiant(adjective, persistent, obstinate, insistent, dogged) |
| demanding(adjective, persistent, obstinate, insistent, dogged) |
| disciplinary(adjective, strong, hard, tough, severe) |
| disobedient(adjective, persistent, obstinate, insistent, dogged) |
| dyed-in-the-wool(adjective, set, strong, hard, tough) |
| exacting(adjective, persistent, obstinate, insistent, dogged) |
| fixed(adjective, confirmed) |
| flinty(adjective, strong, hard, tough, severe) |
| foolhardy(determined, impulsive, stubborn, reckless, heedless) |
| forbidding(adjective, strong, hard, tough, severe) |
| frowning(adjective, strong, hard, tough, severe) |
| grim(adjective, strong, hard, tough, severe) |
| hang-tough(adjective, strong, hard, tough, severe) |
| hard-boiled(adjective, strong, hard, tough, severe) |
| hard-core(adjective, strong, hard, tough, severe) |
| hard-nosed(adjective, strong, hard, tough, severe) |
| hard-shelled(adjective, persistent, obstinate, insistent, dogged) |