| classified(obscure, unknown, clandestine, underground, undisclosed) |
| cloak-and-dagger(obscure, unknown, clandestine, underground, undisclosed) |
| cloak and dagger(expression, idiom, obscure, unknown, unrevealed) |
| clouded(obscure, unknown, clandestine, underground, undisclosed) |
| coherence(adjective, quiet, isolated, lonely, neglected) |
| collected(adjective, shy, stable, peaceful, tranquil) |
| confined(unusual, detached, remote, lonely, inaccessible) |
| connection(adjective, quiet, isolated, lonely, neglected) |
| conspiratorial(obscure, unknown, clandestine, underground, undisclosed) |
| contented(adjective, mild, shy, stable, peaceful) |
| course of thought(expression, adjective, idiom, quiet, isolated) |
| covered(obscure, unknown, clandestine, underground, undisclosed) |
| cryptic(obscure, unknown, clandestine, underground, undisclosed) |
| dead |
| deduction(adjective, quiet, lonely, neglected) |
| deep(obscure, unknown, clandestine, underground, undisclosed) |
| desert |
| dialectic(adjective, quiet, lonely, neglected) |
| discharged(superannuated, emeritus) |
| discreet(clandestine, underground, undisclosed) |