The Collaborative International Dictionary of English v.0.48:

Cooperative \Co*["o]p"er*a*tive\, a.
   Operating jointly to the same end.
   [1913 Webster]

   Cooperative society, a society established on the principle
      of a joint-stock association, for the production of
      commodities, or their purchase and distribution for
      consumption, or for the borrowing and lending of capital
      among its members.

   Cooperative store, a store established by a cooperative
      society, where the members make their purchases and share
      in the profits or losses.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cooperative
    adj 1: involving the joint activity of two or more; "concerted
           action"; "the conjunct influence of fire and strong
           wind"; "the conjunctive focus of political opposition";
           "a cooperative effort"; "a united effort"; "joint
           military activities" [syn: concerted, conjunct,
           conjunctive, cooperative]
    2: done with or working with others for a common purpose or
       benefit; "a cooperative effort" [ant: uncooperative]
    3: willing to adjust to differences in order to obtain agreement
       [syn: accommodative, cooperative]
    n 1: a jointly owned commercial enterprise (usually organized by
         farmers or consumers) that produces and distributes goods
         and services and is run for the benefit of its owners [syn:
         cooperative, co-op]
    2: an association formed and operated for the benefit of those
       using it