secret

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Kept hidden from knowledge or view; concealed.
2. adj. Dependably discreet.
3. adj. Operating in a hidden or confidential manner: a secret agent.
4. adj. Not expressed; inward: their secret thoughts.
5. adj. Not frequented; secluded: wandered about the secret byways of Paris.
6. adj. Known or shared only by the initiated: secret rites.
7. adj. Beyond ordinary understanding; mysterious.
8. adj. Containing information, the unauthorized disclosure of which poses a grave threat to national security.
9. n. Something kept hidden from others or known only to oneself or to a few.
10. n. Something that remains beyond understanding or explanation; a mystery.
11. n. A method or formula on which success is based: The secret of this dish is in the sauce.
12. n. A variable prayer said after the Offertory and before the Preface in the Mass.

Century Dictionary and Cyclopedia

1. Set or kept apart; hidden; concealed. Kept from the knowledge of others; concealed from the notice or knowledge of all except the person or persons concerned; private; not revealed.
2. Privy; not decent to be exposed to view.
3. Occult; mysterious; not seen; not apparent: as, the secret operations of physical causes.
4. Affording privacy; retired; secluded; private.
5. Close, cautious, or discreet in speech, or as regards the disclosure of one's own or another's affairs; faithful in keeping secrets; not given to blabbing or the betrayal of confidence; secretive; reticent.
6. Synonyms and Secret, Latent, Private, Covert, Occult, Clandestine, hidden, concealed, covered, shrouded, veiled, obscure, recondite, close, unknown. The last four of the italicized words, and in their primary sense the participles, express intentional concealment; the others do not. Secret is the most general, but expresses complete concealment. Latent, literally lying concealed, may mean hidden from those most concerned: as, I had a latent sense, feeling, or desire; hence its appropriateness in the expression latent heat. Private (as, it was kept strictly private) emphasizes the fact that some know the thing in question, while others are kept in ignorance. Covert— that is, covered—suggests something underhand or well put out of sight: as, a covert motive, sneer, irony: it is opposed to frank or avowed. Occult suggests mystery that cannot be penetrated: as, the occult operations of nature; occult arts. Clandestine is now always used for studious or artful concealment of an objectionable or dishonorable sort: as, a clandestine correspondence: it applies especially to action.
7. n. Something studiously hidden or concealed; a thing kept from general knowledge; what is not or should not be revealed.
8. n. A hidden, unrevealed, unexplained, or unex-plainable thing; a mystery.
9. n. The key or principle by the application of which some difficulty is solved, or that which is not obvious is explained or made clear; hidden reason or explanation.
10. n. Secrecy.
11. n. In liturgics, a variable prayer in the Roman and some other Latin liturgies, said secretly (see secretly) by the celebrant after the offertory, etc., and immediately before the preface.
12. n. plural The parts of the body which propriety requires to be concealed.
13. n. A concealed piece or suit of armor. Persons fearing assassination sometimes wear such defenses beneath their ordinary dress.
14. n. A skull-cap of steel worn sometimes under and sometimes over the camail.
15. n. A skeleton cap of slender steel bars, affording a good defense against a blow, worn within a hat or other head-covering. It was sometimes made with the bars pivoted in such a way as to fold up, and could be easily carried about the person. See wire hat, under wire.
16. n. A secret device or contrivance.

Wiktionary

1. n. Knowledge that is hidden and intended to be kept hidden. [from later 14th c.]
2. adj. Being or kept hidden. [from late 14th c.]
3. v. To make or keep secret. [from late 16th c.]

GNU Webster's 1913

1. adj. Hidden; concealed.
2. adj. Withdrawn from general intercourse or notice; in retirement or secrecy; secluded.
3. adj. Faithful to a secret; not inclined to divulge or betray confidence; secretive.
4. adj. Separate; distinct.
5. n. Something studiously concealed; a thing kept from general knowledge; what is not revealed, or not to be revealed.
6. n. A thing not discovered; what is unknown or unexplained; a mystery.
7. n. The parts which modesty and propriety require to be concealed; the genital organs.
8. v. To keep secret.

WordNet 3.0

1. adj. not open or public; kept private or not revealed
2. adj. conducted with or marked by hidden aims or methods
3. n. something that baffles understanding and cannot be explained
4. adj. not expressed
5. adj. having an import not apparent to the senses nor obvious to the intelligence; beyond ordinary understanding
6. adj. designed to elude detection
7. n. something that should remain hidden from others (especially information that is not to be passed on)
8. n. information known only to a special group
9. adj. indulging only covertly
10. adj. the next to highest level of official classification for documents
11. adj. not openly made known
12. adj. (of information) given in confidence or in secret
13. adj. hidden from general view or use
14. adj. communicated covertly