| conspiratorial(obscure, unknown, clandestine, underground, undisclosed) |
| covered(obscure, unknown, hidden, clandestine, underground) |
| covert(mysterious, secret, private, reticent, hidden) |
| covertly(quietly, secretly, personally, privately, furtively) |
| cryptic(obscure, mysterious, private, reticent, unknown) |
| dirty-dealing(dishonest, cunning, deceitful, fickle, untrustworthy) |
| dishonest(cunning, deceitful, fickle, untrustworthy, unprincipled) |
| double-crossing(dishonest, cunning, deceitful, fickle, unprincipled) |
| duplicitous(dishonest, cunning, deceitful, fickle, untrustworthy) |
| enigmatic(mysterious, private, reticent, taciturn, covert) |
| feline(mysterious, private, reticent, taciturn, covert) |
| fraudulent(dishonest, cunning, deceitful, secret, private) |
| furtive(obscure, dishonest, cunning, secret, reticent) |
| furtively(clandestine, quietly, secretly, personally, privately) |
| hidden(secret, private, spy, unknowing, underground) |
| hole-and-corner(adjective, secret, private, hidden, spy) |
| hushed(mysterious, secret, private, reticent, taciturn) |
| in camera(expression, clandestine, quietly, secretly, personally) |
| in chambers(expression, mysterious, private, reticent, taciturn) |
| in confidence(expression, adverb, sensitive, confidential, quietly) |