| inflexible(adjective, mean, hard, harsh, stubborn) |
| iron(adjective, mean, hard, tough, harsh) |
| mean(adjective, hard, tough, harsh, unfeeling) |
| mulish(adjective, mean, hard, harsh, inflexible) |
| nark |
| obdurate(adjective, stubborn, pigheaded) |
| obstinate(adjective, mean, hard, harsh, inflexible) |
| perverse(adjective, mean, hard, tough, harsh) |
| pigheaded(adjective, mean, hard, harsh, inflexible) |
| relentless(adjective, mean, hard, tough, harsh) |
| rigid(adjective, mean, hard, harsh, inflexible) |
| roach |
| sculpin |
| set in stone(expression, adjective, idiom, mean, hard) |
| stiff-necked(adjective, mean, hard, tough, harsh) |
| thick-skinned(adjective, mean, hard, tough, harsh) |
| tough(adjective, mean, hard, harsh, inflexible) |
| tough nut to crack(expression, adjective, idiom, mean, hard) |
| unbending(adjective, mean, hard, harsh, inflexible) |
| uncompassionate(adjective, mean, hard, tough, harsh) |