| hanging(adjective, determined, resolute, obstinate, uncompromising) |
| hard(adjective, mean, harsh, cruel, stiff) |
| hard-boiled(adjective, mean, hard, tough, harsh) |
| hard-hearted(adjective, mean, hard, tough, harsh) |
| hard as nails(expression, adjective, idiom, tough, firm) |
| hardboiled(adjective, firm, determined, stiff, unfeeling) |
| hardheaded(adjective, determined, resolute, obstinate, uncompromising) |
| hardline |
| harsh(adjective, mean, hard, cruel, pitiless) |
| hidebound(adjective, determined, resolute, obstinate, uncompromising) |
| hold the fort(expression, adjective, idiom, tough, firm) |
| hold the line(expression, adjective, idiom, tough, firm) |
| immutable(adjective, calm, fixed, constant, impassive) |
| imperishable(adjective, stable, constant, vast, enduring) |
| implacable(adjective, mean, hard, cruel, rigid) |
| in for the long haul(expression, adjective, idiom, stable, constant) |
| incompliant(adjective, tough, severe, firm, difficult) |
| indestructible(adjective, stable, constant, enduring, lasting) |
| indurate(adjective, set, mean, hard, firm) |
| intent(adjective, firm, determined, usual, regular) |