As a Noun:
1. The political belief that the state should control the means of producing everything, and that there should be no private property. English = communism.
2. A person who believes in communism. English = communist.
3. A person who believes that there should be great changes in society and tries to bring about these changes. English = radical.
4. Someone who is very active in trying to bring about extreme political and social change. English = militant.
As a Verb or Adjective:
1. To relate to or be based on communism. English = (be) communist.