secret

classified covert furtive hush-hush mysterious obscure private secluded undercover underground undisclosed unknown unpublished

backdoor close closet dark deep mystic occult unseen

abstruse ambiguous arcane camouflaged cloak-and-dagger clouded conspiratorial covered cryptic disguised enigmatical esoteric mystical on the Q.T. out-of-the-way recondite reticent retired shrouded strange under wraps unenlightened unfrequented unintelligible veiled

aboveboard apparent honest known obvious open public revealed sociable unconcealed

light visible

clear defined explicit forthright legal legitimate

classified confidential covert furtive hush-hush restricted secretive surreptitious

backdoor backstairs close inside sneak

camouflaged cryptic discreet disguised dissembled dissimulated in ambush incognito sly sneaky stealthy sub-rosa top-secret unacknowledged under false pretense under-the-table underhanded

aboveboard forthright honest known open public

clear defined explicit legal legitimate revealed unconcealed

code confidential information key mystery

cipher confidence enigma formula occult oracle password puzzle unknown

classified information magic number privileged information skeleton in cupboard

known public knowledge revelation