| elaborate(adjective, hard, difficult, complex, grand) |
| involved(adjective, hard, difficult, complex, awkward) |
| knotted(adjective, hard, difficult, complex) |
| labyrinthine(adjective, hard, difficult, complex, intricate) |
| leaden(adjective, hard, difficult, complex) |
| ponderous(adjective, hard, difficult, complex) |
| problematic(adjective, hard, tough, difficult, complex) |
| profound(adjective, hard, difficult, complex) |
| sophisticated(adjective, hard, difficult, complex, intricate) |
| sticky(adjective, hard, difficult, complex, awkward) |
| toilful(adjective, hard, difficult, complex, awkward) |
| fatiguing(adjective, dull, difficult, awkward, boring) |
| grueling(adjective, hard, tough, severe, difficult) |
| troublesome(adjective, hard, tough, difficulty, difficult) |
| uphill(adjective, hard, great, tough, easy) |
| demanding(adjective, dull, hard, tough, severe) |
| gruelling |
| tiring(adjective, dull, tough, difficult, awkward) |
| formidable(adjective, tough, severe, difficulty, rough) |
| heavy(adjective, dull, tough, severe, rough) |