| exacting(adjective, hard, tough, severe, cold) |
| feelingless(adjective, hard, tough, severe, cold) |
| ferocious(adjective, animal, mean, cruel, vicious) |
| firm(adjective, mean, hard, tough, harsh) |
| fixed(adjective, mean, hard, tough, harsh) |
| flat(adjective, calm, dull, detached, impassive) |
| going with the flow(expression, adjective, idiom, detached, impassive) |
| habituated(adjective, hard, unfeeling, unsympathetic, hardened) |
| halfhearted(adjective, mean, hard, cool, unpleasant) |
| hanging tough(expression, adjective, mean, hard, stubborn) |
| hard-as-nails(adjective, hard, unfeeling, unsympathetic, hardened) |
| hard-bitten(adjective, hard, careless, indifferent, cruel) |
| hard-nosed(adjective, mean, hard, tough, harsh) |
| ill |
| ill-natured(adjective, evil, negative) |
| immovable(adjective, mean, hard, tough, harsh) |
| impenetrable(adjective, hard, unfeeling, unsympathetic, hardened) |
| impenitent(adjective, hard, tough, careless, indifferent) |
| impious(adjective, hard, unfeeling, unsympathetic, hardened) |
| inaccessible(adjective, hard, unfeeling, unsympathetic, hardened) |