| hidden(hard, tricky, complicated) |
| inexplicable(hard, delicate, complex, tricky, complicated) |
| knotty(hard, tricky, complicated) |
| labyrinthine(hard, tricky, complicated) |
| marvelous(difficult, striking, sophistical) |
| meandering(hard, tricky, complicated) |
| misleading(difficult, striking, sophistical) |
| mysterious(hard, delicate, complex, tricky, complicated) |
| obscure(hard, tricky, complicated) |
| obstinate(hard, tricky, complicated) |
| perplexing(hard, difficult, striking, tricky, complicated) |
| puzzling(hard, tricky, complicated) |
| rambling(hard, tricky, complicated) |
| sophistical(difficult, striking) |
| staggering(difficult, striking, sophistical) |
| striking(difficult, sophistical) |
| tricky(hard, complicated) |
| troublesome(hard, delicate, complex, tricky, complicated) |
| unclear(hard, delicate, complex, tricky, complicated) |
| unfathomable(hard, tricky, complicated) |