| tough(adjective, strong, hard, continue, rough) |
| hard(adjective, strong, continue, rough, harsh) |
| hard-boiled(adjective, hard, tough, rough, harsh) |
| strong(adjective, hard, solid, stiff, sturdy) |
| callous(adjective, hard, rough, harsh, cruel) |
| hands-on |
| hard-handed(adjective, strong, hard, continue) |
| hardy(adjective, strong, hard, continue) |
| pugnacious |
| rugged(adjective, strong, hard, continue) |
| solid(adjective, hard) |
| stiff(adjective, strong, hard, rough, harsh) |
| dense(adjective, strong, hard, solid, stiff) |
| firm(adjective, hard) |
| hard as nails(expression, adjective, idiom, strong, hard) |
| hardened(adjective, strong, hard, tough, careless) |
| impenetrable(adjective, hard, unfeeling, unsympathetic, hardened) |
| inflexible(adjective, strong, hard, rough, harsh) |
| inured(adjective, hard, careless, indifferent, cruel) |
| obdurate(adjective, hard, rough, harsh, careless) |