| furtive(close, clandestine, underground, undisclosed) |
| stealthy(clandestine, underground, undisclosed) |
| surreptitious(clandestine, underground, undisclosed) |
| undercover(clandestine, underground, undisclosed) |
| backdoor(close, sensitive, inside, clandestine, underground) |
| backstairs(close, sensitive, restricted, inside, clandestine) |
| camouflaged(close, clandestine, underground, undisclosed, furtive) |
| clandestine(underground, undisclosed) |
| classified(sensitive, clandestine, underground, undisclosed, sub-rosa) |
| close(inside, clandestine, underground, undisclosed, furtive) |
| confidential(restricted, clandestine, underground, discreet, undisclosed) |
| covert(clandestine, underground, undisclosed) |
| cryptic(close, inside, clandestine, underground, undisclosed) |
| discreet(close, restricted, inside, clandestine, underground) |
| disguised(clandestine, underground, undisclosed) |
| dissembled(close, restricted, clandestine, underground, discreet) |
| dissimulated(close, restricted, inside, clandestine, underground) |
| hush-hush(clandestine, underground, undisclosed) |
| incognito(close, restricted, clandestine, underground, discreet) |
| inside(close, restricted, clandestine, underground, discreet) |