Labor aristocracy or labour aristocracy (also aristocracy of labor) has at least four meanings: as a term with Marxist theoretical underpinnings, as a specific type of trade unionism, and as a shorthand description by revolutionary industrial unions (such as the Industrial Workers of the World) for the bureaucracy of craft-based business unionism. In the nineteenth and early twentieth centuries it was also a phrase used to define better-off members of the working class (as used for example by Jack London in The People of the Abyss).