| recalcitrant(adjective, tough, firm, unreasonable, grim) |
| refractory(adjective, tough, firm, stubborn, unruly) |
| remorseless(adjective, resist, determined, resolute, persistent) |
| unbendable(adjective, resist, determined, resolute, persistent) |
| determined(adjective, tough, firm, resolute, stubborn) |
| firm(adjective, tough, determined, resolute, stubborn) |
| rebellious(adjective, tough, firm, unreasonable, grim) |
| disobedient(adjective, defiant, mischievous) |
| immovable(adjective, hard, firm, determined, resolute) |
| insubordinate(adjective, stubborn, rebellious) |
| steadfast(adjective, firm, determined, unreasonable, grim) |
| fixed(adjective, set, tough, firm, unreasonable) |
| fractious(adjective, cross, unruly, grouchy, raucous) |
| obstinate(adjective, set, hard, stiff, resolute) |
| perverse(adjective, tough, firm, unreasonable, grim) |
| resolute(adjective, hard, firm, determined, rigid) |
| single-minded(adjective, tough, firm, unreasonable, grim) |
| steely(adjective, determined, resolute, strict, obstinate) |
| unadaptable(adjective, set, hard, stiff, rigid) |
| uncooperative |