| backdoor(adjective, close, sensitive, inside, clandestine) |
| backstairs(adjective, close, sensitive, inside, clandestine) |
| camouflaged(close, clandestine, underground, undisclosed, furtive) |
| classified(adjective, sensitive, clandestine, underground, undisclosed) |
| close(inside, clandestine, underground, undisclosed, furtive) |
| confidential(clandestine, underground, undisclosed) |
| covert(clandestine, underground, undisclosed) |
| cryptic(close, inside, clandestine, underground, undisclosed) |
| discreet(close, inside, clandestine, underground, undisclosed) |
| disguised(clandestine, underground, undisclosed) |
| dissembled(close, clandestine, underground, undisclosed, furtive) |
| dissimulated(close, inside, clandestine, underground, undisclosed) |
| furtive(close, clandestine, underground, undisclosed) |
| hush-hush(clandestine, underground, undisclosed) |
| in ambush(expression, adjective, close, sensitive, clandestine) |
| incognito(close, clandestine, underground, undisclosed, furtive) |
| inside(close, clandestine, underground, undisclosed, furtive) |
| on the QT(expression, adjective, idiom, sensitive, clandestine) |
| secret(adjective, sensitive, clandestine, underground, undisclosed) |
| secretive(clandestine, underground, undisclosed) |