| involute(adjective, hard, simple, difficult, complex) |
| serious(adjective, hard, difficult, complex, awkward) |
| sticky(adjective, hard, difficult, delicate, complex) |
| tough(adjective, hard, difficult, complex) |
| arduous(adjective, hard, difficult, complex, awkward) |
| backbreaking(adjective, hard, difficult, complex, awkward) |
| composite(adjective, hard, difficult, complex) |
| esoteric(adjective, hard, difficult, complex) |
| grinding(adjective, hard, difficult, complex, awkward) |
| laborious(adjective, hard, difficult, complex, awkward) |
| nasty(adjective, hard, difficult, complex) |
| operose(adjective, hard, difficult, complex, awkward) |
| painful(adjective, hard, difficult, complex) |
| rough(adjective, hard, difficult, complex, awkward) |
| rugged(adjective, hard, difficult, complex, awkward) |
| tangly(adjective, hard, difficult, complex) |
| toilful(adjective, hard, difficult, complex, awkward) |
| tangled(verb, adjective, hard, simple, obscure) |
| anfractuous(adjective, hard, difficult, complex) |
| burdensome(adjective, hard, difficult, complex, awkward) |