| adamant(adjective, person, feelings, determined, resolute) |
| firm(adjective, set, strong, hard, tough) |
| numb(noun, adjective, hard, tough, severe) |
| stubborn(adjective, characteristic, quality, hard, careless) |
| case-hardened(adjective, hard, careless, indifferent, cruel) |
| cold(adjective, hard, cool, tough, severe) |
| hardhearted(adjective, hard, attitude, careless, cold) |
| indifferent(adjective, hard, cool, careless, cruel) |
| insensible(adjective, hard, cool, tough, severe) |
| inveterate(adjective, set, familiar, usual, fixed) |
| stiffened |
| strengthened(verb, adjective, set, strengthened) |
| thick-skinned(noun, adjective, hard, tough, severe) |
| trained(verb, adjective, skilled, experienced, seasoned) |
| treated |
| unemotional(adjective, hard, cool, tough, severe) |
| unsympathetic(adjective, hard, tough, severe, careless) |
| adamantine(adjective, strong, firm, determined, stiff) |
| annealed(verb, adjective, hard, firm, solid) |
| apathetic(adjective, person, hard, cool, tough) |