Is Senator Barack Obama a Democrat, Socialist, Communist?

Democrat - American Heritage Dictionary

1. An advocate of democracy.
2. One who believes in social equality or discounts distinctions in rank.

Socialist - American Heritage Dictionary (socialism)

1. Any of various theories or systems of social organization in which the means of producing and distributing goods is owned collectively or by a centralized government that often plans and controls the economy.
2. The stage in Marxist-Leninist theory intermediate between capitalism and communism, in which collective ownership of the economy under the dictatorship of the proletariat has not yet been successfully achieved.

Communism - American Heritage Dictionary

1. A theoretical economic system characterized by the collective ownership of property and by the organization of labor for the common advantage of all members.
2. Communism
1. A system of government in which the state plans and controls the economy and a single, often authoritarian party holds power, claiming to make progress toward a higher social order in which all goods are equally shared by the people.
2. The Marxist-Leninist version of Communist doctrine that advocates the overthrow of capitalism by the revolution of the proletariat.