| onerous(adjective, hard, tough, severe, difficult) |
| operose(adjective, tough, severe, painful, problematic) |
| oppressive |
| painful(adjective, tough, severe, problematic, trying) |
| problem(adjective, tough, severe, painful, problematic) |
| problematic(adjective, tough, severe, painful, trying) |
| prohibitive(adjective, tough, severe, painful, problematic) |
| rigid(adjective, tough, severe, painful, problematic) |
| serious |
| severe(adjective, hard, tough, difficult, painful) |
| slavery(noun, work, hard, labor, grind) |
| stiff(adjective, tough, severe, painful, problematic) |
| strenuous(adjective, tough, severe, painful, problematic) |
| task(noun, work, labor) |
| toil(noun, work, hard, labor, grind) |
| toilsome(adjective, tough, severe, painful, problematic) |
| tough(adjective, hard, severe, difficult, painful) |
| tough proposition |
| travail(noun, work, hard, labor, grind) |
| troublesome |