The Collaborative International Dictionary of English v.0.48:

capitalism \cap"i*tal*is`m\ (k[a^]p"[i^]*tal*[i^]z`m), n.
   An economic system based on predominantly private (individual
   or corporate) investment in and ownership of the means of
   production, distribution, and exchange of goods and wealth;
   contrasted with socialism or especially communism, in
   which the state has the predominant role in the economy.

   Syn: capitalist economy.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

capitalism
    n 1: an economic system based on private ownership of capital
         [syn: capitalism, capitalist economy] [ant:
         socialism, socialist economy]