| uphill(adjective, tough, severe, rough, difficult) |
| demanding(adjective, tough, severe, rough, difficult) |
| effortful(adjective, tough, severe, difficult, heavy) |
| fierce(adjective, great, tough, heavy, horrible) |
| ghastly(adjective, bad, terrible, fear, shocking) |
| great(adjective, tough, difficult, big, large) |
| overwhelming(adjective, great, tough, awful, grand) |
| rugged(adjective, hard, severe, evil, rough) |
| staggering(adjective, difficult, overwhelming) |
| challenging(adjective, tough, severe, difficult, awkward) |
| dangerous(adjective, hard, tough, severe, evil) |
| grim(adjective, appearance, bad, severe, manner) |
| horrifying(adjective, awful, terrible, wonderful, grand) |
| important |
| knotty(adjective, hard, severe, rough, difficult) |
| operose(adjective, tough, severe, difficulty, rough) |
| potent(adjective, strong, prevailing, influential, commanding) |
| serious(adjective, bad, hard, difficult, unpleasant) |
| thorny(adjective, bad, difficult, delicate, complex) |
| threatening(adjective, tough, severe, unpleasant, important) |