| unseen(adjective, obscure, dark, secret, unknown) |
| Delphian(adjective, evil, obscure, dark, uncertain) |
| Greek(unfathomable, impenetrable, opaque, unintelligible, puzzling) |
| adverse |
| anagogic(adjective, evil, deep, mysterious, secret) |
| apocryphal(adjective, obscure, secret) |
| auricular |
| backdoor(close, obscure, unknown, inside, clandestine) |
| backstairs(close, mysterious, private, reticent, taciturn) |
| beats me(expression, unfathomable, impenetrable, opaque, unintelligible) |
| between the lines(expression, idiom) |
| beyond comprehension(expression, unfathomable, impenetrable, opaque, unintelligible) |
| blathering(adjective, meaningless) |
| blurred |
| buried(cover, obscure, dark, unknown, hidden) |
| buttoned up(expression, mysterious, private, reticent, taciturn) |
| cagey(mysterious, private, reticent, taciturn, covert) |
| camouflaged(close, obscure, unknown, clandestine, underground) |
| censored |
| clammed up(expression, mysterious, private, reticent, taciturn) |