| hefty(adjective, hard, difficult, heavy, complex) |
| weighty(adjective, hard, difficult, heavy, important) |
| grave(adjective, hard, difficult, important, complex) |
| massive(adjective, hard, difficult, heavy, complex) |
| ponderous(adjective, hard, difficult, heavy, complex) |
| serious(adjective, hard, difficult, important, complex) |
| tough(adjective, hard, difficult, complex) |
| burdensome(adjective, hard, difficult, heavy, complex) |
| grievous(adjective, hard, difficult, complex) |
| leaden(adjective, hard, difficult, complex) |
| massy(adjective, hard, difficult, complex) |
| burly(adjective, hard, difficult, complex) |
| rugged(adjective, hard, difficult, complex) |
| severe(adjective, hard, difficult, complex) |
| notable(noun, adjective, figure, important, star) |
| gargantuan(adjective, large) |
| leader(noun, superior, important, head, boss) |
| major(adjective, great, important, serious) |
| heavy(noun, adjective, order, great, tough) |
| personage(noun, figure, important, individual, star) |