| surreptitious(adjective, dishonest, secret, hidden, spy) |
| clandestine(adjective, adverb, show, dishonest, secret) |
| secret(adjective, quiet, show, dishonest, hidden) |
| covert(adjective, show, secret, reticent, hidden) |
| hush-hush(adjective, adverb, show, informal, dishonest) |
| underground(adjective, secret, unknown, hidden, spy) |
| furtive(adjective, dishonest, secret, reticent, hidden) |
| hidden(adjective, secret, spy, clandestine, underground) |
| hole-and-corner(adjective, secret, private, hidden, spy) |
| hugger-mugger(adjective, quiet, intriguing) |
| confidential(adjective, secret, hidden, spy, clandestine) |
| private(adjective, secret, unknown, hidden, spy) |
| stealthy(adjective, quiet, dishonest, secret, hidden) |
| underhand(adjective, deceitful, secret, hidden, spy) |
| concealed(adjective, obscure, dishonest, secret, hidden) |
| covertly(adverb, underground, secretly, furtively, slyly) |
| secretly(adverb, clandestine, underground, slyly, underhandedly) |
| under wraps(expression, adjective, idiom, show, dishonest) |
| secluded(adjective, secret, unknown, hidden, underground) |
| cloak-and-dagger(adjective, show, full, secret, sly) |