| inexcitable(adjective, callous, insensibility, unexcitable, hard-as-nails) |
| insensate(adjective, hard, unfeeling, unsympathetic, hardened) |
| insensible(adjective, hard, unfeeling, unsympathetic, hardened) |
| insensitive(adjective, hard, unfeeling, unsympathetic, hardened) |
| obstinate(adjective, obstinacy) |
| seasoned(adjective, hard, unfeeling, unsympathetic, hardened) |
| steeled(verb, adjective, hard, unfeeling, unsympathetic) |
| stony(adjective, hard, unfeeling, unsympathetic, hardened) |
| tenacious(adjective, obstinacy) |
| unashamed(adjective, hard, unfeeling, unsympathetic, hardened) |
| unfeeling(adjective, hard, unsympathetic, hardened, toughened) |
| unrepenting(adjective, hard, unfeeling, unsympathetic, hardened) |
| vitrify(verb, close, set, firm, dry) |
| acclimate(verb, dull, develop, blunt, accustom) |
| acclimatize(verb, dull, develop, blunt, accustom) |
| accustom(verb, dull, develop, blunt) |
| accustomed(adjective, hard, unfeeling, unsympathetic, hardened) |
| adapt(verb, dull, develop, blunt, accustom) |
| adjust(verb, dull, develop, blunt, accustom) |
| agglutinate(verb, jellied, calcify, coagulate, gelatinate) |