Concept from Marx, parallel to Durkheim's anomie. In both cases the individual loses the feeling of connection to his / her surroundings, but while Durkheim emphasizes the loss of moral feelings of connectedness (as this is expressed e.g. in religious rituals), Marx emphasizes the body's loss of control over its physical surroundings. In Marx's thought, the worker under capitalism is alienated because the products of his / her labor are removed from the worker's direct control, and replaced by "foreign", "alienated" products (e.g. money).
As the concept of alienation is developed in Marx's Economic and Philosophical Manuscripts (1844), the worker is seen to be alienated in several interconnected ways: (1) from the product of his work (which departs from him into the "system"), (2) from work itself (and hence - since Marx conceives of the human being as a fundamentally creative animal - from himself, from his innermost essence as a creative being), (3) from the species-nature of humanity as such (since creative, productive activity ceases to be a goal in itself and is transformed into a means for individual survival), and (4) from other humans (since their survival competes with his).
As a result, Marx writes, the capitalist "worker becomes poorer the more wealth he produces, the more his production increases in power and extent. The worker becomes an ever cheaper commodity the more commodities he produces. The devaluation of the human world grows in direct proportion to the increase in value of the world of things. Labor not only produces commodities; it also produces itself and the workers as a commodity and it does so in the same proportion in which it produces commodities in general" (Marx 1844).