| grin and bear it(verb, expression, idiom, phrasal verb, hold) |
| hack(verb, hold, go, accept, endure) |
| hang in there(verb, expression, idiom, phrasal verb, take) |
| hard-line(tough, difficult, wild, awkward, obstinate) |
| harden |
| headstrong(tough, sharp, difficult, awkward, practical) |
| hold off(verb, expression, take, bear, endure) |
| hold up |
| hurl defiance at(expression, idiom, disregard, ignore, challenge) |
| ignore(disregard, challenge, resist, frustrate, confront) |
| immovable(tough, difficult, obstinate, stubborn, willful) |
| incompliant(tough, difficult, wild, awkward, obstinate) |
| incurable(tough, difficult, wild, awkward, obstinate) |
| indocile(tough, difficult, wild, awkward, obstinate) |
| indomitable(tough, difficult, wild, awkward, obstinate) |
| inflexible(strong, definite, obstinate, stubborn, willful) |
| insoluble(tough, difficult, wild, awkward, obstinate) |
| intractable(adjective, sharp, difficult, practical, shrewd) |
| keep at it(expression, idiom) |
| keep driving(verb, expression, advance, continue, extend) |