In Class Definitions

Capitalism - Capitalism is a social system based on the principle of individual rights. Politically, it is the system of laissez-faire (freedom). Legally it is a system of objective laws (rule of law as opposed to rule of man). Economically, when such freedom is applied to the sphere of production its’ result is the free-market.

http://www.capitalism.org/

Communism
What is Communism?

Communism is the doctrine of the conditions of the liberation of the proletariat.

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What is the proletariat?

The proletariat is that class in society which lives entirely from the sale of its labor and does not draw profit from any kind of capital; whose weal and woe, whose life and death, whose sole existence depends on the demand for labor – hence, on the changing state of business, on the vagaries of unbridled competition. The proletariat, or the class of proletarians, is, in a word, the working class of the 19th century.^[1]

http://www.marxists.org/archive/marx/works/1847/11/prin-com.htm

Free Enterprise – An economic system where few restrictions are placed on business activities and ownership. In this system, governments generally have minimal ownership of enterprises in the market place. This system aims for limited restrictions on trade and minimal government intervention.

Read more: http://www.investopedia.com/terms/f/free_enterprise.asp#ixzz2EF8esLB2

http://www.investopedia.com/terms/f/free_enterprise.asp#axzz2EF8UECvg

Free Market - an economic system with only a small amount of government control, in which prices and earnings are decided by the level of demand for, and production of goods and services

http://dictionary.cambridge.org/dictionary/british/free-market