a false allegation of murder; the term refers specifically to a recurring rumor from 12th century Europe that Jews were kidnapping Christian children and using their blood for ritual purposes. A famous example of the blood libel is recounted in the "Nun Prioress's Tale" from Chaucer's *Canterbury Tales*. In this and other versions of the story, the events are absurd and feature perverse miracles
Frequently occurrences of the blood libel were accompanied by a wave of mass murder of Jewish residents of the city. In many cases, the zealots would force the authorities to try random Jews for the alleged crime; these trials were, naturally, travesties.
The last case of a blood libel resulting in murder was the Kielce pogrom of 1946. 200 Jewish survivors of the Final Solution were being transported back to Poland when a boy (who had disappeared for a couple of days) told the police he had been kidnapped by Jews. The police went to a hostel where returning Holocaust survivors were staying, and massacred 37 of them.
Sometimes the phrase "blood libel" is used to refer to similar allegations against primarily non-Jewish groups; for example, many nationalities have been accused of kidnapping children to harvest their organs and sell them to rich patients in the developed world.
Although the details have changed over the last millenium, the blood libel retains core elements of sadistic fantasy, psychological projection, and crass opportunism.