| complex(adjective, hard, difficult) |
| elaborate(adjective, hard, difficult, complex) |
| grave(adjective, hard, tough, severe, difficult) |
| hefty(adjective, hard, difficult, complex) |
| involved(adjective, hard, difficult, complex, awkward) |
| knotted(adjective, hard, difficult, complex) |
| oppressive(adjective, hard, difficult, complex) |
| problematic(adjective, hard, difficult, complex) |
| taxing(adjective, hard, difficult, complex) |
| toilful(adjective, hard, difficult, complex, awkward) |
| trying(adjective, hard, difficult, complex) |
| complicated(adjective, hard, difficult, complex, awkward) |
| grinding(adjective, hard, difficult, complex, awkward) |
| nasty(adjective, hard, difficult, complex) |
| weighty(adjective, hard, difficult, complex) |
| grueling(adjective, hard, tough, difficult, awkward) |
| industrious(adjective, work, tedious, labour, hardworking) |
| time-consuming |
| gruelling |
| heavy(adjective, tough, severe, rough, difficult) |