Definition:
Alienation is a state of feeling estranged or separated from one's environment, work, products of work, or self.
Marxist Context:
In Karl Marx's theory, it refers to the condition of workers in a capitalist society. Workers lose control over their work and the things they produce, becoming mere cogs in a machine. They become alienated from:
The product of their labor.
The process of labor (work becomes forced).
Their fellow workers (competition replaces cooperation).