| difficult(adjective, hard, tough, rough, problematic) |
| arduous(hard, tough, severe, rough, difficult) |
| tough(hard, severe, rough, difficult, painful) |
| demanding(hard, tough, severe, rough, difficult) |
| exacting(tough, severe, rough, difficult, painful) |
| laborious(hard, tough, severe, rough, difficult) |
| not easy(expression, tough, severe, painful, problematic) |
| operose(hard, tough, severe, rough, difficult) |
| rough |
| rugged(adjective, difficult, rigorous) |
| severe(hard, tough, difficult, painful, problematic) |
| titanic(tough, severe, painful, problematic, trying) |
| toilsome(hard, tough, severe, difficult, painful) |
| uphill(hard, tough, severe, rough, difficult) |
| abstruse |
| ambitious(tough, severe, painful, problematic, trying) |
| backbreaker(tough, severe, painful, problematic, trying) |
| bothersome(tough, severe, painful, problematic, trying) |
| brutal |
| burdensome(hard, tough, severe, difficult, painful) |