| difficult(adjective, hard, heavy, complex) |
| heavyweight(adjective, hard, difficult, heavy, important) |
| leaden(adjective, hard, difficult, heavy, complex) |
| hard(adjective, difficult, heavy, complex) |
| trying(adjective, hard, difficult, heavy, complex) |
| arduous(adjective, hard, difficult, heavy, complex) |
| backbreaking(adjective, hard, difficult, heavy, complex) |
| big(adjective, good, solid, importance, heavy) |
| massy(adjective, hard, difficult, complex) |
| stodgy(adjective, dull, hard, difficult, complex) |
| burly(adjective, hard, difficult, solid, heavy) |
| esoteric(adjective, hard, difficult, complex) |
| laborious(adjective, hard, difficult, heavy, complex) |
| lumpish(adjective, hard, difficult, complex, gravity) |
| rough(adjective, hard, difficult, heavy, complex) |
| sore(adjective, hard, difficult, complex, angry) |
| stressful(adjective, hard, difficult, complex) |
| toilsome(adjective, hard, difficult, complex) |
| troubled(adjective, hard, difficult, complex) |
| complex(adjective, hard, difficult) |