| laborious(adjective, work, hard, tough, severe) |
| hard(adjective, tough, severe, rough, difficult) |
| arduous(adjective, hard, tough, severe, rough) |
| backbreaking(adjective, hard, difficult, complex, awkward) |
| difficult(adjective, hard, tough, severe, rough) |
| toilsome(adjective, hard, tough, difficult, complex) |
| punishing(adjective, hard, difficult, complex) |
| severe(adjective, hard, tough, difficult, violent) |
| tough(adjective, hard, severe, rough, difficult) |
| burdensome(adjective, hard, tough, difficult, complex) |
| painful(adjective, hard, difficult, complex) |
| ambitious(adjective, work, hard, difficult, complex) |
| rugged(adjective, hard, severe, difficult, violent) |
| serious(adjective, hard, difficult, important, complex) |
| sticky(adjective, hard, difficult, complex, awkward) |
| intricate(adjective, hard, difficult, complex, awkward) |
| knotty(adjective, hard, severe, rough, difficult) |
| rough(adjective, hard, difficult, complex, awkward) |
| thorny(adjective, hard, difficult, complex) |
| tricky(adjective, hard, difficult, complex, awkward) |