| mixed(adjective, hard, fancy, difficult, complex) |
| perplexing(adjective, hard, fancy, difficult, complex) |
| problematic(adjective, hard, fancy, difficult, complex) |
| puzzling(adjective, hard, fancy, difficult, complex) |
| recondite(adjective, hard, fancy, difficult, complex) |
| sophisticated(adjective, hard, fancy, difficult, complex) |
| troublesome(adjective, hard, fancy, difficult, complex) |
| various(adjective, hard, fancy, difficult, complex) |
| wheels within wheels(expression, adjective, idiom, hard, fancy) |
| complicated(adjective, difficult, complex, intricate, thorny) |
| daedal(caught, multiplex, gordian) |
| dense(adjective, difficult, complex, intricate, thorny) |
| full of twists and turns(expression, adjective, idiom, difficult, complex) |
| hi tech(expression, complicated, caught, multiplex, daedal) |
| high-tech(caught, multiplex, daedal, gordian) |
| high tech(expression, caught, multiplex, daedal, gordian) |
| problematical(adjective, difficult, complex, intricate, thorny) |
| thorny(adjective, difficult, complex, intricate) |