not made explicit; "the unexpressed terms of the agreement"; "things left unsaid"; "some kind of unspoken agreement"; "his action is clear but his reason remains unstated"
based on custom rather than documentation; "an unwritten law"; "rites...so ancient that they well might have had their unwritten origins in Aurignacian times"- J.L.T.C.Spence
information known only to a special group; "the secret of Cajun cooking"
something that should remain hidden from others (especially information that is not to be passed on); "the combination to the safe was a secret"; "he tried to keep his drinking a secret"
the next to highest level of official classification for documents
not expressed; "secret (or private) thoughts"
indulging only covertly; "a secret alcoholic"
communicated covertly; "their secret signal was a wink"; "secret messages"
not open or public; kept private or not revealed; "a secret formula"; "secret ingredients"; "secret talks"