Epikoros (or **Apikoros ** or Apikores;, pl. Epikorsim; ) is a Jewish term figuratively meaning "a heretic", cited in the Mishnah, that refers to an individual who does not have a share in the World to Come: "All of Israel have a part in the World to Come. But the following have no part in the World to Come: One who says that the resurrection of the dead is not biblical, or that the Torah is not from Heaven, or the Epicurean."

• Jerusalem Talmud, "All of the Jewish people have a share in the World-to-Come, as it is stated: “And your people also shall be all righteous, they shall inherit the land forever; the branch of My planting, the work of My hands, for My name to be glorified” (Isaiah 60:21). And these [are the exceptions,] the people who have no share in the World-to-Come [...] One who says: There is no resurrection of the dead derived from the Torah, and one who says: The Torah did not originate from Heaven, and an epikoros[.]"
• Babylonian Talmud, The rabbinic literature uses the term Epikoros without a specific reference to the Greek philosopher Epicurus, but it is apparent that the term is derived from his name. Epicurus was a pagan philosopher whose views contradicted Jewish scripture, the strictly monotheistic conception of God in Judaism, and the Jewish belief in the World to Come; see. The Talmudic interpretation is that the Aramaic word is derived from the root-word (PQR; lit. licentious), hence disrespect, and accordingly: "§ [The mishna teaches that those who have no share in the World-to-Come include] an epikoros. Rav and Rabbi Ḥanina both say: This is one who treats a Torah scholar with contempt. Rabbi Yoḥanan and Rabbi Yehoshua ben Levi say: This is one who treats another with contempt before a Torah scholar." According to Maimonides, scorning a Talmid Chakham ( "Torah scholar") is actually a singular case of disrespecting the entire Torah or its rabbinic scholar-sages. In his work Mishneh Torah (Yad, Teshuvah 3:8), Maimonides rules that an Epikoros is a person who denies that God communicates with humans through prophecy; one who denies the prophecy of Moses; or one who denies God's knowledge of the affairs of humans (i.e., one who maintains there is no divine providence). Maimonides probably encountered the name of Epicurus some time between composing his commentary on the Mishnah and before composing The Guide for the Perplexed. In the first source, he erroneously states that the rabbinic term epikoros is an Aramaic word; in the Guide, Maimonides has become aware of the atheistic doctrine of the philosopher by that name. He cites the source of his information as Alexander of Aphrodisias's treatise On Providence. Following the Christian censorship of the Talmud, starting with the aftermath of the Disputation of Barcelona and during the Roman Inquisition and the Spanish Inquisition, the term spread within the Jewish classical texts. Censors shunned expressions like minim ("sectarian"), which they viewed as referring to the Christian faith, and replaced them with the term Epikoros or Epicurus (hence a heretic as the Church would also persecute heretics). The censors also replaced terms that refer to Christians with the word, an abbreviation of , a belief that both Jews and their Christian censors abhorred.