What is anti-Semitism? The Definition of Anti-Semitism is the first book-length study to explore this central question in the context of the new anti-Semitism. Previous efforts to define 'anti-Semitism' have been complicated by the disreputable origins of the term, the discredited sources of its etymology, the diverse manifestations of the concept, and the contested politics of its applications. Nevertheless the task is an important one, not only because definitional clarity is required for the term to be understood, but also because the current conceptual confusion prevents resolution of many incidents in which anti-Semitism is manifested. The Definition of Anti-Semitism explores the various ways in which anti-Semitism has historically been defined, demonstrates the weaknesses in prior efforts, and develops a new definition of anti-Semitism, especially in the context of the 'new anti-Semitism' in American higher education.