| rugged(adjective, hard, severe, difficult, unpleasant) |
| serious(adjective, hard, difficult, complex) |
| stressful(adjective, hard, difficult, complex) |
| taxing(adjective, hard, difficult, complex) |
| tough(adjective, hard, severe, difficult, awful) |
| trying(adjective, hard, difficult, complex) |
| unbearable(adjective, hard, difficult, complex) |
| weighty(adjective, hard, difficult, complex) |
| cruel(adjective, mean, hard, severe, difficult) |
| heartrending(adjective, hard, difficult, complex) |
| impossible(adjective, hard, difficult, complex) |
| laborious(adjective, hard, difficult, complex) |
| sensitive(adjective, hard, difficult, complex) |
| sticky(adjective, hard, difficult, complex) |
| toilsome(adjective, hard, difficult, complex) |
| tricky(adjective, hard, difficult, complex) |
| perturbing(verb, adjective, bad, hard, severe) |
| troubling(verb, adjective, bad, hard, severe) |
| irritating(noun, verb, adjective, adverb, distressing) |
| worrisome(adjective, hard, severe, happy, pain) |