| unruly(adjective, tough, difficult, unpleasant, determined) |
| unsympathetic(adjective, mean, hard, severe, harsh) |
| austere(adjective, appearance, strong, hard, tough) |
| authoritarian(adjective, strong, hard, tough, severe) |
| bovine(adjective, determined, resolute, obstinate, uncompromising) |
| demanding(adjective, hard, tough, easy, severe) |
| difficult(adjective, hard, tough, severe, wild) |
| hardened(adjective, set, hard, tough, firm) |
| opinionated(adjective, tough, violent, wild, determined) |
| rebellious(adjective, tough, firm, inflexible, stubborn) |
| single-minded(adjective, tough, firm, harsh, cruel) |
| stabile |
| stalwart(adjective, strong, hard, sound, tough) |
| unappeasable(adjective, mean, severe, harsh, cruel) |
| unconquerable(adjective, resistance, insurmountable) |
| unmoved(adjective, cold, indifferent, determined, fixed) |
| wilful(adjective, determined, resolute, uncompromising, unshakeable) |
| brass-bound(adjective, determined, resolute, obstinate, uncompromising) |
| callous(adjective, mean, hard, severe, rough) |
| decided(adjective, resolute) |