Few concepts carry the weight and power of the term genocide. The word's profound significance is bound to its unique role as a moral and legal marker of the very worst type of human behavior. Morally, genocide refers to acts of horrific violence such as mass murder, state terror, and other strategies of brutal repression. The term names an ethical boundary beyond which a government forfeits its legitimacy and society descends into barbarism. Legally, genocide refers to the intentional destruction of a group as such, a crime so severe that it demands immediate and total condemnation. As the United Nations Special Rapporteur on the subject stated, "Genocide is the ultimate crime and the gravest violation of human rights it is possible to commit."

The term genocide has a highly specific origin, rooted in two related sources: the invention of the word in 1943 by Polish jurist Raphael Lemkin; and its definition, several...