se'or

The lexica are unanimous and give a single sense: HALOT glosses שְׂאֹר as sourdough or leaven, BDB and DCH likewise print one entry, and none records a second sense or a figurative extension. All five occurrences are legal (Exodus 12:15, 19; 13:7; Leviticus 2:11; Deuteronomy 16:4), which is why the word is treated here as monosemous. The Septuagint renders both שְׂאֹר and חָמֵץ with ζύμη, collapsing a distinction the Hebrew lexica preserve: שְׂאֹר is the starter, technically not itself food, while חָמֵץ is the fermented product. Propp describes the household practice behind the term, bread leavened by preserving a chunk of the previous day's dough, and argues that destroying the שְׂאֹר symbolically severed a household's continuity with the past year, which suits a spring New Year rite (Exodus 1-18, 434-43); Childs and Tigay treat the exodus rationale of Deuteronomy 16:3 as the historicizing layer over an older agricultural festival. On the altar prohibition of Leviticus 2:11, Milgrom's reading of fermentation as decay incompatible with the altar (Leviticus 1-16, 188-91, citing Plutarch, Quaestiones Romanae 109 on the flamen Dialis) has dominated the field for a generation; Levine and Haran instead stress the polarity between the stable holiness of the altar, marked by the covenant of salt in Leviticus 2:13, and the changing character of ordinary food, and Wenham argues more simply that nothing living was to be burned on the altar. Klawans cautions that the priestly system draws ritual rather than moral boundaries, so the identification of leaven with evil should not be read back into P. That identification is a Second Temple and later Jewish development, articulated in the rabbinic image of the שְׂאוֹר שֶׁבָּעִיסָה, the leaven in the dough, as the evil inclination (b. Berakhot 17a), and inherited by early Christian writers through the ζύμη passages of the New Testament (Bokser, ABD 6:755-65).