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.
      [1913 Webster]

   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.
        [1913 Webster]

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]

Moby Thesaurus II by Grady Ward, 1.0:

175 Moby Thesaurus words for "admission":
   Americanization, OK, acceptance, access, acculturation,
   acknowledging, acknowledgment, acquisition, adit, admissibility,
   admission fee, admittance, admitting, adoption, affidavit,
   affiliation, affirmation, allegation, allowance, allowing,
   anchorage, appointment, appreciation, assertion, asseveration,
   assimilation, assumption, attest, attestation, averment,
   avouchment, avowal, baptism, brokerage, carfare, cellarage, charge,
   charges, charter, citizenship by naturalization,
   citizenship papers, completeness, comprehension, comprehensiveness,
   comprisal, compurgation, conceding, concession, confession,
   consent, cover charge, coverage, culture shock, declaration,
   demand, deposition, derivation, disclosure, dispensation,
   divulgement, divulgence, dockage, dues, eligibility, embodiment,
   embracement, encompassment, enlistment, enrollment, entrance,
   entrance fee, entree, entry, envisagement, exaction, exactment,
   exhaustiveness, fare, fee, getting, hire, immission, import,
   importation, importing, inauguration, inclusion, inclusiveness,
   income, incoming, incorporation, induction, infiltration, ingoing,
   ingress, ingression, initiation, input, insertion, insinuation,
   installation, instatement, institution, instrument in proof,
   intake, interpenetration, introduction, introgression,
   intromission, intrusion, investiture, leakage, leave,
   legal evidence, liberty, license, license fee, membership,
   nationalization, naturalization, naturalized citizenship, okay,
   openness, ordination, owning, owning up, papers, participation,
   patent, penetration, percolation, permission, permission to enter,
   pilotage, portage, profession, receipt, receival, receiving,
   reception, recognition, release, revelation, rite of confession,
   salvage, scot, scot and lot, seepage, shot, shrift,
   special permission, statement, storage, sworn evidence,
   sworn statement, sworn testimony, taking, tariff, testimonial,
   testimonium, testimony, ticket, ticket of admission, tolerance,
   toleration, toll, towage, unbosoming, vouchsafement, waiver, way,
   wharfage, whole, witness, word



Bouvier's Law Dictionary, Revised 6th Ed (1856):

ADMISSION, in corporations or companies. The act of the corporation or
company by which an individual acquires the rights of a member of such
corporation or company.
     2. In trading and joint stock corporations no vote of admission is
requisite; for any person who owns stock therein, either by original
subscription or by conveyance, is in general entitled to, and cannot be
refused, the rights and privileges of a member. 3 Mass. R. 364; Doug. 524; 1
Man. & Ry. 529.
     3. All that can be required of the person demanding a transfer on the
books, is to prove to the corporation his right to the property. See 8 Pick.
90.
     4. In a Mutual Insurance Company, it has been held, that a person may
become a member by insuring his property, paying the premium and deposit-
money, and rendering himself liable to be assessed according to the rules of
the corporation. 2 Mass. R. 315.