| feelingless(adjective, hard, indifferent, cruel, unsympathetic) |
| fierce(adjective, mean, severe, harsh, cruel) |
| flagituous(adjective, bad behavior) |
| flinthearted |
| gothly(adjective, bad behavior) |
| gratuitous(adjective, mean, severe, harsh, cruel) |
| habituated(adjective, hard, unfeeling, unsympathetic, hardened) |
| hard-as-nails(adjective, hard, unfeeling, unsympathetic, hardened) |
| hard-bitten(adjective, hard, careless, indifferent, cruel) |
| hard as nails(expression, adjective, idiom, hard, indifferent) |
| hard of heart(expression, idiom) |
| hatchet job(expression, adjective, mean, severe, harsh) |
| having a killer instinct(expression, adjective, idiom, mean, severe) |
| hostile(adjective, coldhearted) |
| impassive(adjective, hard, careless, indifferent, cruel) |
| impenetrable(adjective, hard, cruel, unfeeling, unsympathetic) |
| impenitent(adjective, hard, careless, indifferent, cruel) |
| impious(adjective, hard, unfeeling, unsympathetic, hardened) |
| implacable(adjective, mean, hard, severe, harsh) |
| inaccessible(adjective, hard, unfeeling, unsympathetic, hardened) |