The Collaborative International Dictionary of English v.0.48:

Organization \Or`gan*i*za"tion\
   ([^o]r`gan*[imac]*z[=a]"sh[u^]n), n. [Cf. F. organisation.]
   [1913 Webster]
   1. The act of organizing; the act of arranging in a
      systematic way for use or action; as, the organization of
      an army, or of a deliberative body. "The first
      organization of the general government." --Pickering.
      [1913 Webster]

   2. The state of being organized.
      [1913 Webster]

   3. That which is organized; an organized existence; an
      organism; specif. (Biol.), an arrangement of parts for the
      performance of the functions necessary to life.
      [1913 Webster]

            The cell may be regarded as the most simple, the
            most common, and the earliest form of organization.
                                                  --McKendrick.
      [1913 Webster]

   4. Specifically: A group of persons associated together for a
      common purpose and having a set of rules which specify the
      relations of the individual members to the whole gorup.
      [PJC]

   5. The manner in which something is organized; the relations
      included in an organized state or condition; as, the
      organization of the department permits ad hoc groups to
      form.
      [PJC]

            What is organization but the connection of parts in
            and for a whole, so that each part is, at once, end
            and means?                            --Coleridge.
      [1913 Webster]

WordNet (r) 3.0 (2006):

organization
    n 1: a group of people who work together [syn: organization,
         organisation]
    2: an organized structure for arranging or classifying; "he
       changed the arrangement of the topics"; "the facts were
       familiar but it was in the organization of them that he was
       original"; "he tried to understand their system of
       classification" [syn: arrangement, organization,
       organisation, system]
    3: the persons (or committees or departments etc.) who make up a
       body for the purpose of administering something; "he claims
       that the present administration is corrupt"; "the governance
       of an association is responsible to its members"; "he quickly
       became recognized as a member of the establishment" [syn:
       administration, governance, governing body,
       establishment, brass, organization, organisation]
    4: the act of organizing a business or an activity related to a
       business; "he was brought in to supervise the organization of
       a new department" [syn: organization, organisation]
    5: an ordered manner; orderliness by virtue of being methodical
       and well organized; "his compulsive organization was not an
       endearing quality"; "we can't do it unless we establish some
       system around here" [syn: organization, organisation,
       system]
    6: the activity or result of distributing or disposing persons
       or things properly or methodically; "his organization of the
       work force was very efficient" [syn: organization,
       organisation]
    7: the act of forming or establishing something; "the
       constitution of a PTA group last year"; "it was the
       establishment of his reputation"; "he still remembers the
       organization of the club" [syn: constitution,
       establishment, formation, organization, organisation]