| cautious(adjective, quiet, gentle, peaceful, reserved) |
| circumspect(adjective, wary, guarded, sneaky, covert) |
| clammed up(expression, adjective, close, quiet, soft) |
| clamming up(expression, adjective, quiet, reserved, secret) |
| clandestinely |
| close-lipped(adjective, quiet, reserved, secret, private) |
| closed |
| cold(quiet, gentle, shy, unfriendly, aloof) |
| collected(quiet, gentle, aloof, peaceful, reserved) |
| compact |
| confused(adjective, shy, closed, sheep) |
| conspiratorial(adjective, clandestine, underground, undisclosed, sneaky) |
| cool(quiet, gentle, shy, unfriendly, aloof) |
| could hear a pin drop(expression, adjective, idiom, close, quiet) |
| covered(clandestine, underground, undisclosed) |
| crafty(adjective, mean, smooth, dishonest, deceitful) |
| crooked(mean, smooth, dishonest, cunning, deceitful) |
| crowded |
| cunning(adjective, mean, smooth, dishonest, deceitful) |
| curious(strange, unknown, concealed, inexplicable, unexplained) |