Alienation (n.) is alienation both from one's own nature and from other men. In capitalism, productive activity is competitive rather than cooperative, making the other into an alien and hostile being. Love and trust are replaced by bargaining and exchange.
Alienation (n.) is neither a subjective nor an ontological concept, but a sociohistorical normative category that points to a deplorable state of affairs that should be overcome.
Alienation (n.) is the fundamental evil of capitalist society.
Alienation (n.) is the idea that our consciousness is just fine but that our reality is perverted. It is in the material world as it is that man is alienated.
Alienation (n.) is the independent life which the worker gives to the object (by giving a piece of himself to it) only to then be confronted by that object as hostile and alien.
Alienation (n.) is undergone by both the proletarian and the propertied classes but the latter feels comfortable in their alienation, knowing that to posses is to possess a morsel of human existence.