Epikoros

Epikoros (or apikoros or apikores; Hebrew: אֶפִּיקוֹרוֹס, romanized: ˌʾeppikoˈros, lit. 'Epicurus', pl. epikorsim; Yiddish: אַפּיקורס, romanized: apiˈkoyres) 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 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, Sanhedrin 10:1

The rabbinic literature uses the term epikoros without a specific reference to the Greek philosopher Epicurus, but some understand that the term is derived from his name. Epicurus was a materialist philosopher whose views contradicted Hebrew Bible, the strictly monotheistic conception of God in Judaism, and the Jewish belief in the World to Come (see Epicureanism § Philosophy).

The Talmudic interpretation is that the Aramaic word is derived from the Semitic root פק"ר‎ (p-k-r, lit. 'licentious'), and accordingly:

§ [The Mishnah 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.

— Babylonian Talmud, Sanhedrin 99b:14

Marcus Jastrow, in his dictionary, identifies the term as, in fact, being an enlargement of פק"ר, which was then supported by its phonetic coincidence with the famed pagan philosopher.