| willful(adjective, tough, firm, difficult, resist) |
| determined(adjective, tough, firm, resolute, impulsive) |
| hard-nosed(adjective, mean, strong, hard, tough) |
| intransigent(adjective, determined, resolute, obstinate, stubborn) |
| opinionated(adjective, tough, firm, determined, resolute) |
| resolute(adjective, tough, determined, obstinate, stubborn) |
| self-willed(adjective, tough, firm, difficult, determined) |
| unrelenting(adjective, mean, strong, hard, tough) |
| contrary(adjective, difficult, determined, awkward, resolute) |
| contumacious(adjective, tough, firm, determined, unreasonable) |
| fixed(adjective, mean, hard, firm, determined) |
| recalcitrant(adjective, tough, firm, difficult, awkward) |
| relentless(adjective, mean, strong, hard, tough) |
| stiff-necked(adjective, mean, strong, hard, tough) |
| adamantine(adjective, strong, hard, tough, firm) |
| hard(adjective, mean, strong, tough, determined) |
| inexorable(adjective, mean, strong, hard, tough) |
| persistent(adjective, tough, firm, determined, resolute) |
| set(adjective, determined, resolute, obstinate, uncompromising) |
| unbending(adjective, mean, strong, hard, tough) |