| firm(adjective, serious, resolute, persistent, unwavering) |
| fitted out(adjective, unsubmissive) |
| gritty |
| hard(adjective, unfeeling, unsympathetic, hardened, callous) |
| hard-edged(adjective, toughened, cynical, hard-boiled, hard-bitten) |
| hard-nosed(adjective, hard, unfeeling, unsympathetic, hardened) |
| hard as nails(expression, adjective, idiom, determined, serious) |
| heroic |
| impassive(adjective, hard, unfeeling, unsympathetic, hardened) |
| impenitent(adjective, hard, unfeeling, unsympathetic, hardened) |
| indifferent(adjective, hard, unfeeling, unsympathetic, hardened) |
| indomitable |
| inexcitable(adjective, callous, unexcitable) |
| inflexible(adjective, hard, unfeeling, unsympathetic, hardened) |
| insensate(adjective, hard, unfeeling, unsympathetic, hardened) |
| insensible(adjective, hard, unfeeling, unsympathetic, hardened) |
| insensitive(adjective, hard, tough, unfeeling, unsympathetic) |
| insentient(adjective, hard, unfeeling, unsympathetic, hardened) |
| matter of fact(expression, adjective, idiom, callous, unexcitable) |
| poker-faced(adjective, callous, unexcitable) |