| stubborn(adjective, characteristic, quality, strong, hard) |
| dogged(adjective, tough, firm, resist, determined) |
| pigheaded(adjective, tough, firm, difficult, resist) |
| headstrong(adjective, hard, resist, determined, resolute) |
| obstinate(adjective, tough, resist, determined, resolute) |
| mulish(adjective, strong, hard, tough, difficult) |
| willful(adjective, tough, difficult, resist, wild) |
| hardheaded(adjective, strong, hard, tough, resist) |
| opinionated(adjective, tough, firm, determined, resolute) |
| pertinacious(adjective, tough, difficult, resist, wild) |
| perverse(adjective, tough, firm, resist, determined) |
| stiff-necked(adjective, strong, hard, tough, firm) |
| tenacious(adjective, tough, firm, difficult, resist) |
| unyielding(adjective, strong, hard, tough, deliberate) |
| obdurate(adjective, strong, hard, tough, deliberate) |
| persistent(adjective, tough, firm, determined, unreasonable) |
| adamant(adjective, strong, hard, tough, firm) |
| adamantine(adjective, strong, hard, tough, severe) |
| determined(adjective, tough, firm, unreasonable, stiff) |
| hard(adjective, strong, tough, determined, resolute) |