Adjective form of Communism. Typically used for a person who believes in Communism; A person who belives that the ideal society is stateless, religionless, moneyless and classeless where the means of production (things like farms, shops, factories, roads) are owned by all members of the society, in other words a socialist, anarchist, atheist society. There may be some cases where non Atheists can be communists (such as Christian communist movement).
Like most political definitions, Communism is vaguely defined. Are members of the Chrisitan communist movement communists even though they believe in god? Was the Soviet Union Communist even though it went as far from Anarchism as can be?
What we all agree on however, is that Communists all want to abolish private ownership of the means of production (which doesn't get us anywhere, because Socialism has the same definition). Therefore Communists are fundamentally opposed to Capitalists and Aristocrats/pro-Feudalism peeps.
Vlad: hYello mY naem is-a Vlad
Heinrich: Good God! Why are you writing such bad grammar?!
Vlad: r U sume exclusioninmanist Gremmar Nazi?
Heinrich: Yes, you must be a Grammar Communist...
Vlad: Yaaeh!! all forms of Gremmar must be accepted. aBolish Priv8 owhnership of Dicktionaries!