| impassive(adjective, hard, careless, indifferent, cruel) |
| implacable(adjective, hard, tough, harsh, cruel) |
| indifferent(adjective, hard, careless, cruel, apathetic) |
| indurated(adjective, hard, careless, indifferent, cruel) |
| inexorable(adjective, hard, tough, harsh, cruel) |
| inflexible(adjective, hard, careless, indifferent, cruel) |
| inhuman(adjective, hard, tough, harsh, cruel) |
| inhumane(adjective, hard, tough, harsh, cruel) |
| insensate(adjective, hard, careless, indifferent, cruel) |
| insensible(adjective, hard, careless, indifferent, cruel) |
| insentient(adjective, hard, careless, indifferent, cruel) |
| insolent |
| intolerant(adjective, hard, tough, harsh, cruel) |
| inured(adjective, hard, careless, indifferent, cruel) |
| merciless(adjective, hard, tough, harsh, cruel) |
| murderous(adjective, hard, tough, harsh, cruel) |
| pitiless(adjective, hard, tough, harsh, cruel) |
| relentless(adjective, hard, tough, harsh, cruel) |
| rigorous(adjective, hard, tough, harsh, cruel) |
| ruthless(adjective, hard, tough, harsh, cruel) |