| weighty(adjective, hard, difficult, heavy, complex) |
| complex(adjective, hard, difficult, tricky, problematic) |
| grievous(adjective, hard, difficult, complex, painful) |
| intricate(adjective, hard, difficulty, difficult, complex) |
| punishing(verb, adjective, hard, difficult, complex) |
| backbreaking(adjective, hard, difficult, heavy, complex) |
| cruel(adjective, hard, difficult, complex, painful) |
| grinding(adjective, hard, difficult, complex) |
| hefty(adjective, dull, hard, difficult, complex) |
| impossible(adjective, hard, difficulty, difficult, complex) |
| precarious(adjective, hard, difficult, complex) |
| problematic(adjective, hard, difficult, complex) |
| sore(adjective, hard, difficult, complex, painful) |
| ambitious(adjective, hard, difficult, complex) |
| disturbing(adjective, hard, difficult, complex) |
| knotted(adjective, hard, difficulty, difficult, complex) |
| labyrinthine(adjective, hard, difficulty, difficult, complex) |
| operose(adjective, hard, difficult, complex) |
| sensitive(adjective, hard, difficult, complex) |
| stubborn(adjective, hard, difficulty, difficult, complex) |