| sensitive(adjective, hard, difficult, complex) |
| hidden(verb, adjective, hard, evil, obscure) |
| abstruse(noun, adjective, hard, sound, easy) |
| cryptic(adjective, evil, sharp, obscure, dark) |
| deep(adjective, hard, sound, easy, evil) |
| arcane(adjective, evil, obscure, strange, deep) |
| mysterious(adjective, hard, evil, obscure, dark) |
| concealed(adjective, evil, obscure, dark, strange) |
| mystic(adjective, evil, obscure, dark, deep) |
| mystical(adjective, hard, evil, obscure, dark) |
| confidential(adjective, secret, private, clandestine, underground) |
| intimate(adjective, secret, private, mental, inner) |
| cabalistic(adjective, evil, obscure, strange, deep) |
| inside(adjective, individual, secret, private, mental) |
| personal(adjective, private, mental, inner, speciality) |
| enigmatic(adjective, hard, evil, sharp, obscure) |
| sophisticated |
| unfathomable(adjective, hard, obscure, difficult, strange) |
| heavy(adjective, easy, severe, obscure, slang) |
| individual(adjective, private, mental, inner, speciality) |