Secret

n. information that is confidential or classified; mystery, unexplained phenomenon; method or procedure that is known only by a select group of people

adj. classified, confidential; clandestine, covert; hidden, latent

Secrecy is the practice of sharing information among a group of people, which can be as small as one person, while hiding it from others. That which is kept hidden is known as the secret. Secrecy is often controversial. Many people claim that, at least in some situations, it is better for everyone if everyone knows all the facts—there should be no secrets. The closely allied, perhaps even synonymous notions of confidentiality and privacy are often considered virtues. Although this belief is held by many people, most argue that it is taken out of context. William Penn wrote, "It is wise not to seek a secret; and honest, not to reveal one."[1]
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Noun
1. 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"
(hypernym) information, info
(hyponym) confidence
2. information known only to a special group; "the secret of Cajun cooking"
(synonym) arcanum
(hypernym) information, info
(hyponym) esoterica
3. something that baffles understanding and cannot be explained; "how it got out is a mystery"; "it remains one of nature's secrets"
(synonym) mystery, enigma, closed book
(hypernym) perplexity
Adjective
1. not open or public; kept private or not revealed; "a secret formula"; "secret ingredients"; "secret talks"
(similar) concealed
2. 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"
(synonym) clandestine, cloak-and-dagger, hole-and-corner(a), hugger-mugger, hush-hush, on the quiet(p), surreptitious, undercover, underground
(similar) covert
3. not openly made known; "a secret marriage"; "a secret bride"
(synonym) unavowed
(similar) unacknowledged
4. communicated covertly; "their a secret signal was a wink"; "secret messages"
(similar) covert
5. not expressed; "secret (or private) thoughts"
(synonym) private
(similar) inward
6. 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
(similar) concealed
7. hidden from general view or use; "a privy place to rest and think"; "a secluded romantic spot"; "a secret garden"
(synonym) privy, secluded
(similar) private
8. (of information) given in confidence or in secret; "closet information"; "this arrangement must be kept confidential"; "their secret communications"
(synonym) closet(a), confidential
(similar) private
9. indulging only covertly; "a closet alcoholic"; "closet liberals"
(synonym) closet(a)
(similar) covert
10. 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"
(synonym) mysterious, mystic, mystical, occult, orphic
(similar) esoteric
11. the next to highest level of official classification for documents
(similar) classified

adj. secret, inner, close; low key, off the record; hidden, covert; cryptic, esoteric, ulterior; undercover, clandestine

n. secret, mystery; secrecy, confidentiality, privacy; stealthiness

(v. t.)
To keep secret.
  

(a.)
Withdraw from general intercourse or notice; in retirement or secrecy; secluded.
  

(a.)
The parts which modesty and propriety require to be concealed; the genital organs.
  

(a.)
Something studiously concealed; a thing kept from general knowledge; what is not revealed, or not to be revealed.
  

(a.)
Separate; distinct.
  

(a.)
Hidden; concealed; as, secret treasure; secret plans; a secret vow.
  

(a.)
Faithful to a secret; not inclined to divulge or betray confidence; secretive.
  

(a.)
A thing not discovered; what is unknown or unexplained; a mystery.