| mean(adjective, hard, cool, harsh, unpleasant) |
| narrow(adjective, hateful, impatient, prejudiced, fanatical) |
| rocklike |
| stony-hearted(adjective, cold, cruel, unfeeling, unsympathetic) |
| unflagging(adjective, tenacious) |
| unmerciful(adjective, mean, hard, tough, harsh) |
| unsentimental(adjective, hardened, uncompromising, toughened, cynical) |
| acrimonious(adjective, tough, severe, harsh, cruel) |
| apathetic(adjective, person, mean, hard, cool) |
| balky(tough, firm, unreasonable, grim, inflexible) |
| case-hardened(adjective, hard, careless, indifferent, cruel) |
| dead set(adjective, determined, resolute, uncompromising, unshakeable) |
| dense(adjective, strong, hard, tough, sturdy) |
| disobedient |
| flintlike(adjective, tenacious) |
| granitelike |
| hanging(adjective, determined, resolute, obstinate, uncompromising) |
| indefatigable(adjective, tenacious) |
| indifferent(adjective, mean, hard, cool, unpleasant) |
| indomitable(adjective, strong, hard, tough, difficult) |