secret
noun.
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
noun.
information known only to a special group
the secret of Cajun cooking
Synonym: arcanum
noun.
something that baffles understanding and cannot be explained
how it got out is a mystery|it remains one of nature's secrets
adj.
not open or public; kept private or not revealed
a secret formula|secret ingredients|secret talks
adj.
conducted with or marked by hidden aims or methods
clandestine intelligence operations|cloak-and-dagger activities behind enemy lines|hole-and-corner intrigue|secret missions|a secret agent|secret sales of arms|surreptitious mobilization of troops|an undercover investigation|underground resistance
adj.
not openly made known
a secret marriage|a secret bride
Synonym: unavowed
adj.
communicated covertly
their secret signal was a wink|secret messages
adj.
not expressed
secret (or private) thoughts
Synonym: private
adj.
designed to elude detection
a hidden room or place of concealment such as a priest hole|a secret passage|the secret compartment in the desk
Synonym: hidden
adj.
hidden from general view or use
a privy place to rest and think|a secluded romantic spot|a secret garden
Synonym: privy, secluded
adj.
(of information) given in confidence or in secret
this arrangement must be kept confidential|their secret communications
Synonym: confidential
adj.
indulging only covertly
a secret alcoholic
adj.
having an import not apparent to the senses nor obvious to the intelligence; beyond ordinary understanding
mysterious symbols|the mystical style of Blake|occult lore|the secret learning of the ancients
adj.
the next to highest level of official classification for documents