The Collaborative International Dictionary of English v.0.48:

Admission \Ad*mis"sion\, n. [L. admissio: cf. F. admission. See
   Admit.]
   1. The act or practice of admitting.
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   2. Power or permission to enter; admittance; entrance;
      access; power to approach.
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            What numbers groan for sad admission there! --Young.
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   3. The granting of an argument or position not fully proved;
      the act of acknowledging something ?serted;
      acknowledgment; concession.
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            The too easy admission of doctrines.  --Macaulay.
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   4. (Law) Acquiescence or concurrence in a statement made by
      another, and distinguishable from a confession in that an
      admission presupposes prior inquiry by another, but a
      confession may be made without such inquiry.
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   5. A fact, point, or statement admitted; as, admission made
      out of court are received in evidence.
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   6. (Eng. Eccl. Law) Declaration of the bishop that he
      approves of the presentee as a fit person to serve the
      cure of the church to which he is presented. --Shipley.
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   Syn: Admittance; concession; acknowledgment; concurrence;
        allowance. See Admittance.
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WordNet (r) 3.0 (2006):

admission
    n 1: the act of admitting someone to enter; "the surgery was
         performed on his second admission to the clinic" [syn:
         admission, admittance]
    2: an acknowledgment of the truth of something
    3: the fee charged for admission [syn: entrance fee,
       admission, admission charge, admission fee, admission
       price, price of admission, entrance money]
    4: the right to enter [syn: entree, access, accession,
       admission, admittance]