| persistent(adjective, strain, firmness, labour, hardiness) |
| firm(noun, adjective, hard, strain, rough) |
| stiff(adjective, hard, tough, strain, rough) |
| stubborn(adjective, characteristic, quality, obstinate, stubbornness) |
| hard(adjective, tough, strain, rough, firm) |
| strong(adjective, strain, firmness, labour, hardiness) |
| stable(adjective, strain, firmness, labour, hardiness) |
| unyielding(adjective, hard, tough, strain, rough) |
| intractable(adjective, control, order, tough, difficulty) |
| unruly(adjective, control, order, difficult, resist) |
| recalcitrant(adjective, control, order, tough, difficult) |
| rigid(adjective, hard, tough, strain, firm) |
| obstinate(adjective, control, order, difficulty, resist) |
| contumacious(adjective, tough, firm, determined, negative) |
| disobedient(adjective, persistent, resistance, obstinate, stubborn) |
| resistant(adjective, strain, firm, solid, firmness) |
| ungovernable(adjective, control, order, difficult, resist) |
| steadfast(adjective, strain, firmness, labour, hardiness) |
| unmanageable(adjective, control, order, hard, tough) |
| headstrong(adjective, tough, firm, determined, negative) |