The Collaborative International Dictionary of English v.0.48:

Confidence \Con"fi*dence\, n. [L. confidentia firm trust in,
   self-confidence: cf. F. confidence.]
   1. The act of confiding, trusting, or putting faith in;
      trust; reliance; belief; -- formerly followed by of, now
      commonly by in.
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            Society is built upon trust, and trust upon
            confidence of one another's integrity. --South.
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            A cheerful confidence in the mercy of God.
                                                  --Macaulay.
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   2. That in which faith is put or reliance had.
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            The Lord shall be thy confidence.     --Prov. iii.
                                                  26.
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   3. The state of mind characterized by one's reliance on
      himself, or his circumstances; a feeling of
      self-sufficiency; such assurance as leads to a feeling of
      security; self-reliance; -- often with self prefixed.
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            Your wisdom is consumed in confidence;
            Do not go forth to-day.               --Shak.
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            But confidence then bore thee on secure
            Either to meet no danger, or to find
            Matter of glorious trial.             --Milton.
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   4. Private conversation; (pl.) secrets shared; as, there were
      confidences between them.
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            Sir, I desire some confidence with you. --Shak.
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   Confidence game, any swindling operation in which advantage
      is taken of the confidence reposed by the victim in the
      swindler; several swindlers often work together to create
      the illusion of truth; -- also called con game.

   Confidence man, a swindler.

   To take into one's confidence, to admit to a knowledge of
      one's feelings, purposes, or affairs.

   Syn: Trust; assurance; expectation; hope.
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              I am confident that very much be done. --Boyle.
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   2. Trustful; without fear or suspicion; frank; unreserved.
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            Be confident to speak, Northumberland;
            We three are but thyself.             --Shak.
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   3. Having self-reliance; bold; undaunted.
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            As confident as is the falcon's flight
            Against a bird, do I with Mowbray fight. --Shak.
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   4. Having an excess of assurance; bold to a fault;
      dogmatical; impudent; presumptuous.
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            The fool rageth and is confident.     --Prov. xiv.
                                                  16.
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   5. Giving occasion for confidence. [R.]
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            The cause was more confident than the event was
            prosperous.                           --Jer. Taylor.
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WordNet (r) 3.0 (2006):

confidence
    n 1: freedom from doubt; belief in yourself and your abilities;
         "his assurance in his superiority did not make him
         popular"; "after that failure he lost his confidence"; "she
         spoke with authority" [syn: assurance, self-assurance,
         confidence, self-confidence, authority, sureness]
    2: a feeling of trust (in someone or something); "I have
       confidence in our team"; "confidence is always borrowed,
       never owned" [ant: diffidence, self-distrust, self-
       doubt]
    3: a state of confident hopefulness that events will be
       favorable; "public confidence in the economy"
    4: a trustful relationship; "he took me into his confidence";
       "he betrayed their trust" [syn: confidence, trust]
    5: a secret that is confided or entrusted to another; "everyone
       trusted him with their confidences"; "the priest could not
       reveal her confidences"

Moby Thesaurus II by Grady Ward, 1.0:

140 Moby Thesaurus words for "confidence":
   acceptation, acception, acquiescence, anticipation, aplomb,
   arcanum, arrogance, aspiration, assumption, assurance,
   assured faith, assuredness, balance, belief, boldness, brashness,
   brass, cabala, certainty, certitude, cheek, cheerful expectation,
   classified information, cocksureness, confidential communication,
   confidentially, confidentness, contemplation, conviction, coolness,
   courage, credence, credit, credulity, crust, dauntlessness,
   dependence, desire, doomed hope, enigma, equability, equanimity,
   equilibrium, esoterica, expectancy, expectation, face,
   fair prospect, faith, fearlessness, fervent hope, gall, good cheer,
   good hope, great expectations, guarded secret, hermetics,
   high hopes, hope, hopeful prognosis, hopefulness, hopes, hoping,
   hoping against hope, hubris, imminence, impudence, in confidence,
   in privacy, intimately, level head, levelheadedness, mettle,
   mystery, mystery of mysteries, nerve, overconfidence, oversureness,
   overweening, overweeningness, personal matter, poise, pomposity,
   positiveness, possession, prayerful hope, presence of mind,
   presumption, pride, private matter, privately,
   privileged communication, privity, probability, profound secret,
   promise, prospect, prospects, reception, reliance, reliance on,
   resolution, restraint, restricted information,
   sanguine expectation, sealed book, secret, security,
   self-assurance, self-command, self-confidence, self-control,
   self-importance, self-possession, self-reliance, self-restraint,
   settled belief, spirit, stock, store, subjective certainty,
   sureness, surety, suspension of disbelief, tenacity, the occult,
   thought, trust, unafraidness, unapprehensiveness, unastonishment,
   unbashfulness, undauntedness, unfearfulness, unfearingness,
   unshrinkingness, unshyness, untimidness, well-grounded hope,
   well-regulated mind