secret in WordNet English dictionary

1. information known only to a special group
   "the secret of Cajun cooking"
   secret  arcanum 
   
2. something that baffles understanding and cannot be explained
   "how it got out is a mystery"; "it remains one of nature's secrets"
   mystery  enigma  secret  closed book 
   
3. 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"
   secret 
   

1. 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"
   clandestine  cloak-and-dagger  hole-and-corner  hugger-mugger  hush-hush  secret  surreptitious  undercover  underground 
   
2. (of information) given in confidence or in secret
   "this arrangement must be kept confidential"; "their secret communications"
   confidential  secret 
   
3. 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"
   hidden  secret 
   
4. 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"
   mysterious  mystic  mystical  occult  secret  orphic 
   
5. not expressed
   "secret (or private) thoughts"
   secret  private 
   
6. hidden from general view or use
   "a privy place to rest and think"; "a secluded romantic spot"; "a secret garden"
   privy  secluded  secret 
   
7. the next to highest level of official classification for documents
   secret 
   
8. not open or public; kept private or not revealed
   "a secret formula"; "secret ingredients"; "secret talks"
   secret 
   
9. not openly made known
   "a secret marriage"; "a secret bride"
   unavowed  secret 
   
10. indulging only covertly
    "a secret alcoholic"
    secret 
    
11. communicated covertly
    "their secret signal was a wink"; "secret messages"
    secret