| complicated(adjective, hard, difficult, complex, awkward) |
| grinding(adjective, hard, difficult, complex, awkward) |
| serious(adjective, hard, easy, difficult, important) |
| thorny(adjective, hard, difficult, complex) |
| tricky(adjective, hard, difficult, complex, awkward) |
| ambitious(adjective, work, hard, difficult, complex) |
| onerous(adjective, dull, hard, great, tough) |
| plodding(adjective, work, hard, difficult, complex) |
| sticky(adjective, hard, difficult, complex, awkward) |
| tight(adjective, hard, difficult, complex) |
| elaborate(adjective, hard, difficult, complex, exertion) |
| weighty(adjective, hard, difficult, heavy, complex) |
| grave(adjective, hard, tough, severe, difficult) |
| grievous(adjective, hard, difficult, complex) |
| hefty(adjective, dull, hard, difficult, complex) |
| intricate(adjective, hard, difficult, complex, awkward) |
| leaden(adjective, hard, difficult, complex) |
| profound(adjective, hard, difficult, complex) |
| stubborn(adjective, hard, difficult, complex) |
| Byzantine(adjective, hard, difficult, complex) |