| imperceivable(obscure, dark, secret, unknown, hidden) |
| in the dark(expression, idiom, obscure, dark, unknown) |
| incalculable |
| incognito(unknown, clandestine, underground, nameless) |
| incognizable |
| indiscernible(obscure, dark, unknown, hidden, imperceptible) |
| little-known |
| mystic(obscure, dark, secret, unknown, hidden) |
| mystical(obscure, dark, secret, unknown, hidden) |
| not made known(expression, idiom) |
| obscured(cover, obscure, dark, equivocal, imperceptible) |
| off the record(expression, adjective, idiom, personal, confidential) |
| out-of-the-way(obscure, unknown, clandestine, underground, unrevealed) |
| out of view(expression, idiom, obscure, dark, unknown) |
| puzzling |
| recondite(obscure, dark, secret, unknown, hidden) |
| remote(cover, obscure, dark, equivocal, ulterior) |
| removed(personal, confidential, hush-hush) |
| reticent(obscure, unknown, clandestine, underground, unrevealed) |
| retired(obscure, unknown, personal, clandestine, underground) |