The Collaborative International Dictionary of English v.0.48:

Communism \Com"mu*nism\, n. [F. communisme, fr. commun common.]
   A scheme of equalizing the social conditions of life;
   specifically, a scheme which contemplates the abolition of
   inequalities in the possession of property, as by
   distributing all wealth equally to all, or by holding all
   wealth in common for the equal use and advantage of all.
   [1913 Webster]

   Note: At different times, and in different countries, various
         schemes pertaining to socialism in government and the
         conditions of domestic life, as well as in the
         distribution of wealth, have been called communism.
         [1913 Webster]

WordNet (r) 3.0 (2006):

communism
    n 1: a form of socialism that abolishes private ownership
    2: a political theory favoring collectivism in a classless
       society

Moby Thesaurus II by Grady Ward, 1.0:

112 Moby Thesaurus words for "communism":
   Bolshevism, Castroism, Communist Information Bureau,
   Communist Party, Maoism, Marxian socialism, Marxism,
   Marxism-Leninism, Nazism, Stalinism, Titoism, Trotskyism,
   bipartisanship, centralism, coaction, coadjuvancy,
   coadministration, coagency, cochairmanship, codirectorship,
   collaboration, collaborativeness, collective farm, collectivism,
   collectivity, collegiality, collusion, commensalism, common effort,
   common enterprise, common ownership, communal effort, communalism,
   communion, communitarianism, community, complicity, concert,
   concord, concordance, concurrence, constitutionalism, cooperation,
   cooperative society, cooperativeness, democracy,
   democratic centralism, democratism, dialectical materialism, duet,
   duumvirate, ecumenicalism, ecumenicism, ecumenism, esprit,
   esprit de corps, fascism, federalism, fellow feeling, fellowship,
   feudalism, feudality, governmentalism, harmony, imperialism,
   iron curtain, joining of forces, joint effort, joint operation,
   kibbutz, kolkhoz, mass action, monarchism, morale,
   mutual assistance, mutualism, mutuality, national socialism,
   neofascism, octet, parliamentarianism, parliamentarism, pluralism,
   political principles, pooling, pooling of resources,
   profit sharing, public ownership, pulling together, quartet,
   quintet, reciprocity, republicanism, revisionism, royalism, septet,
   sextet, sharecropping, socialism, solidarity, state ownership,
   statism, symbiosis, synergism, synergy, team spirit, teamwork,
   town meeting, trio, triumvirate, troika, united action