Herem (Hebrew: חֵרֶם, also Romanized chērem, ḥērem) is the highest ecclesiastical censure in the Jewish community. It is the total exclusion of a person from the Jewish community. It is a form of shunning, and is similar to vitandus excommunication in the Catholic Church. Cognate terms in other Semitic languages include the Arabic term ḥarām (forbidden, taboo, off-limits, sacred or immoral), and the Ethiopic `irm (meaning accursed).
Arguably the most famous case of a herem is that of Spinoza, the seventeenth century philosopher.
Other famous subjects of a herem were early Russian communists Leon Trotsky and Grigory Zinoviev. Sometime in 1918, while Ukraine was under German occupation, the rabbis of Odessa pronounced herem against Trotsky, Zinoviev, and other Jewish Bolshevik leaders in the synagogue.
Although developed from the Biblical ban, excommunication, as employed by the Rabbis during Talmudic times and during the Middle Ages, it became a rabbinic institution, the object of which was to preserve Jewish solidarity. A system of laws was gradually developed by Rabbis, by means of which this power was limited, so that it became one of the modes of legal punishment by rabbinic courts. While it did not entirely lose its arbitrary character, since individuals were allowed to pronounce the ban of excommunication on particular occasions, it became chiefly a legal measure resorted to by a judicial court for certain prescribed offenses.
The three terms herem (censure), excommunication, herem (war or property) the devotion of enemies by annihilation in the Tanakh, and herem (priestly gift) the devotion of property to a kohen, are all three variant English transliterations of the same Hebrew noun. This noun comes from the semitic root Ḥ-R-M.