When Sarah Palin accused journalists and pundits of "blood libel" in the wake of the deadly Arizona shootings, she reached deep into one of medieval history's most sordid chapters to make her point.

The term "blood libel" is not well known, but it is highly charged — a direct reference to a time when many European Christians accused Jews of kidnapping and murdering Christian children to obtain their blood. Jews were tortured and executed for crimes they did not commit, emblematic of anti-Semitism so virulent that some scholars recoiled Wednesday at Palin's use of the term.

In a video posted to her Facebook page early Wednesday, the 2008 GOP vice presidential candidate accused the U.S. media of inciting hatred and violence after the shooting that gravely wounded U.S. Rep. Gabrielle Giffords. Palin has been criticized for marking Giffords' district with the cross hairs of a gun sight during last fall's campaign.

"But, especially within hours of a tragedy unfolding, journalists and pundits should not manufacture a blood libel that serves only to incite the very hatred and violence they purport to condemn. That is reprehensible," she said.

But some experts on the history of blood libel took exception to Palin's use of the term.

"In her own thinking, I just don't understand the logical use of this word," said Ronnie Hsia, a professor of history at Pennsylvania State University who has written two books about blood libel. "I think it's inappropriate and I frankly think if she or her staff know about the meaning of this word, I think it's insulting to the Jewish people."

Said Jerome Chanes, a research fellow at the Center for Jewish Studies at the City University of New York: "It's a classic case of, I don't know what you want to call it, semantic corruption."

Palin's aides did not immediately respond to an e-mail Wednesday.

Blood libel dates back to the 12th century in England, France, Germany and elsewhere in Europe, when many Christians believed that Jews killed children, usually boys, for supposed rituals including re-enacting the crucifixion of Christ, historians say. According to the belief, Jews would torture and kill the children and use their blood, often to make matzoh, the "bread of affliction" that is central to celebrating the Jewish holiday of Passover.

"That was the Christian fantasy," Hsia said. "In some of these cases, the Jewish community was interrogated and in many cases people were tortured into confession and executed. Sometimes the Christian authorities tried to intervene, but sometimes the authorities also believed in the supposed allegations."

Belief in blood libel spread through northern Europe before fading in the 18th century. But it reappeared in the 19th and 20th centuries, with cases as recently as one in Poland after World War II. The best-known case was in modern-day Ukraine where a Jew named Mendel Beilis was arrested in 1911 after a boy was found dead. Beilis was imprisoned for two years, but eventually acquitted, despite the attempt by prosecutors to pin responsibility for the murder on him based on his religion.

Palin is not the first to use the term in the context of the Tucson shootings. In the past few days, it has been used by commentator John Hayward on the conservative website Human Events and in a Wall Street Journal opinion piece by Glenn Harlan Reynolds, a University of Tennessee law professor who runs the website Instapundit.

And the term has been used before, in other situations far removed from its original meaning. In 1982, for example, Israeli Prime Minister Menachem Begin said charges that his country stood by while Lebanese Phalangists slaughtered Palestinian refugees "constitute a blood libel against every Jew, everywhere."

Abraham Foxman, national director of the Anti-Defamation League, said in a written statement that it was inappropriate to blame Palin for the shooting and that she had the right to defend herself against such criticism.

"Still, we wish that Palin had not invoked the phrase 'blood libel,'" said Foxman, whose organization fights anti-Semitism. "While the term "blood libel" has become part of the English parlance to refer to someone being falsely accused, we wish that Palin had used another phrase, instead of one so fraught with pain in Jewish history."

Matt Goldish, a professor of Jewish and European history at Ohio State, said Palin's usage of the term led him to believe she did not know its history, but that he did not think many people would find it offensive.

"The combination of the words, blood and libel, obviously kind of ring up together," Goldish said. "And you can imagine somebody who's obviously heard the phrase in their distant past have it come up on their radar screen."