noun

1. any economic theory or system based on the ownership of all property by the community as a whole
2. 1. a hypothetical stage of socialism, as formulated by Marx, Engels, Lenin, and others, to be characterized by a classless and stateless society and the equal distribution of economic goods, and to be achieved by revolutionary and dictatorial, rather than gradualistic, means
   2. the form of government of various, esp. former, socialist states which profess to be working toward this stage by means of state planning and control of the economy, a one-party political structure, and an emphasis on the requirements of the state rather than on individual liberties
3. 1. a political movement for establishing a communist system
   2. the doctrines, methods, etc. of the Communist parties
4. loosely communalism
5. loosely any political ideas or activity thought of as being leftist or subversive

Etymology: Fr communisme < commun (< OFr comun) + isme: see common & -ism