NOUN (5)

1. an admission of misdeeds or faults;

2. a written document acknowledging an offense and signed by the guilty party;

3. (Roman Catholic Church) the act of a penitent disclosing his sinfulness before a priest in the sacrament of penance in the hope of absolution;

4. a public declaration of your faith;

5. the document that spells out the belief system of a given church (especially the Reformation churches of the 16th century);

The Collaborative International Dictionary of English v.0.48:

Confession \Con*fes"sion\, n. [F. confession, L. confessio.]
   1. Acknowledgment; avowal, especially in a matter pertaining
      to one's self; the admission of a debt, obligation, or
      crime.
      [1913 Webster]

            With a crafty madness keeps aloof,
            When we would bring him on to some confession
            Of his true state.                    --Shak.
      [1913 Webster]

   2. Acknowledgment of belief; profession of one's faith.
      [1913 Webster]

            With the mouth confession is made unto salvation.
                                                  --Rom. x. 10.
      [1913 Webster]

   3. (Eccl.) The act of disclosing sins or faults to a priest
      in order to obtain sacramental absolution.
      [1913 Webster]

            Auricular confession . . . or the private and
            special confession of sins to a priest for the
            purpose of obtaining his absolution.  --Hallam.
      [1913 Webster]

   4. A formulary in which the articles of faith are comprised;
      a creed to be assented to or signed, as a preliminary to
      admission to membership of a church; a confession of
      faith.
      [1913 Webster]

   5. (Law) An admission by a party to whom an act is imputed,
      in relation to such act. A judicial confession settles the
      issue to which it applies; an extrajudical confession may
      be explained or rebutted. --Wharton.
      [1913 Webster]

   Confession and avoidance (Law), a mode of pleading in which
      the party confesses the facts as stated by his adversary,
      but alleges some new matter by way of avoiding the legal
      effect claimed for them. --Mozley & W.
      [1913 Webster]

   Confession of faith, a formulary containing the articles of
      faith; a creed.

   General confession, the confession of sins made by a number
      of persons in common, as in public prayer.

   Westminster Confession. See Westminster Assembly, under
      Assembly.
      [1913 Webster]

WordNet (r) 3.0 (2006):

confession
    n 1: an admission of misdeeds or faults
    2: a written document acknowledging an offense and signed by the
       guilty party
    3: (Roman Catholic Church) the act of a penitent disclosing his
       sinfulness before a priest in the sacrament of penance in the
       hope of absolution
    4: a public declaration of your faith
    5: the document that spells out the belief system of a given
       church (especially the Reformation churches of the 16th
       century)