| unsympathetic(adjective, mean, hard, careless, indifferent) |
| brutal(adjective, terrible behavior) |
| bullheaded(adjective, strong, hard, tough, firm) |
| cold(adjective, close, hard, cool, severe) |
| cool(adjective, severe, cold, sensitive, shy) |
| decisive(adjective, resolute) |
| demanding(adjective, severe) |
| distant(adjective, cool, correct, cold, shy) |
| exacting(adjective, severe) |
| hard-boiled(adjective, mean, strong, hard, tough) |
| hard-hearted(adjective, mean, hard, harsh, inflexible) |
| immutable(adjective, hard, firm, rigid, inflexible) |
| reliable(adjective, resolute, persistent, dedicated, unwavering) |
| savage(adjective, terrible behavior) |
| self-willed(tough, firm, difficult, determined, resolute) |
| single-minded(adjective, tough, harsh, cruel, determined) |
| standoffish(adjective, cool, cold, shy, unfriendly) |
| straight |
| straightening(verb, straightening) |
| tense(adjective, hard, firm, solid, stiff) |