| difficult(adjective, hard, tough, delicate, complex) |
| tricky(adjective, hard, open, difficult, delicate) |
| knotty(adjective, hard, difficult, delicate, complex) |
| precarious(adjective, hard, open, difficult, complex) |
| intricate(adjective, hard, difficult, delicate, complex) |
| thorny(adjective, hard, difficult, delicate, complex) |
| complicated(adjective, hard, difficult, delicate, complex) |
| sensitive(adjective, hard, difficult, delicate, uncertain) |
| hard(adjective, difficult, delicate, complex, tricky) |
| tough(adjective, hard, difficult, complex) |
| complex(adjective, hard, difficult, delicate, awkward) |
| sticky(adjective, hard, difficult, complex) |
| involved(adjective, hard, difficult, delicate, complex) |
| tight(adjective, hard, difficult, complex) |
| debatable(adjective, open, certain, uncertain, doubtful) |
| labyrinthine(adjective, hard, difficult, complex, intricate) |
| byzantine(adjective, hard, difficult, complex, intricate) |
| painful(adjective, hard, difficult, complex) |
| rugged(adjective, hard, difficult, delicate, uncertain) |
| trying(adjective, hard, difficult, complex) |