| problematic(adjective, hard, difficult, complex) |
| relentless(adjective, appearance, mean, strong, hard) |
| toilful(adjective, hard, difficult, complex, awkward) |
| agonizing(adjective, strong, sharp, tender, pain) |
| caustic(adjective, mean, evil, sharp, nasty) |
| dour(adjective, hard, tough, firm, attitude) |
| excruciating(adjective, sharp, tender, pain, intense) |
| keen(adjective, clear, strong, cool, tough) |
| pitiless(adjective, person, mean, hard, tough) |
| spartan(adjective, simple, plain, pure, grim) |
| terrible(adjective, appearance, bad, hard, great) |
| unyielding(adjective, appearance, mean, clear, strong) |
| awful(adjective, bad, great, tender, offensive) |
| cold(adjective, calm, mean, hard, cool) |
| heavy(adjective, strong, hard, tough, difficult) |
| obdurate(adjective, mean, strong, hard, tough) |
| stiff(adjective, hard, tough, rough, firm) |
| tyrannical(adjective, difficult, harsh, severity) |
| dangerous(adjective, help, bad, hard, tough) |
| inhuman(adjective, person, mean, hard, tough) |