| viscous(adjective, feature, characteristic, secure, structure) |
| tough(adjective, feature, characteristic, hard, difficult) |
| tricky(adjective, hard, easy, difficult, delicate) |
| difficult(adjective, hard, delicate, complex, awkward) |
| oppressive(adjective, moist, close, hard, difficult) |
| glutinous(adjective, feature, characteristic, secure, structure) |
| hard(adjective, difficult, complex, awkward, demanding) |
| knotty(adjective, hard, difficult, delicate, informal) |
| thorny(adjective, hard, difficult, complex, problematic) |
| nasty(adjective, hard, difficult, terrible, dirty) |
| rough(adjective, hard, easy, difficult, complex) |
| sensitive(adjective, hard, difficult, delicate, complex) |
| tight(adjective, hard, easy, difficult, complex) |
| trying(adjective, hard, difficult, complex) |
| viscid(adjective, feature, characteristic, secure, structure) |
| laborious(adjective, hard, difficult, complex, awkward) |
| rugged(adjective, hard, difficult, complex, awkward) |
| complicated(adjective, hard, difficult, delicate, complex) |
| painful(adjective, hard, difficult, complex, embarrassing) |
| complex(adjective, hard, difficult) |