sibling-in-law

Where the authorities disagree

Why the levir is a yavam.

• Rabbi Shlomo Pappenheim of Breslau (1740-1814) traces it to the biliteral ב-ם, whose core sense shows in bam, "in them" or "through them," which he further breaks down into two monoliteral roots, the beis of "in, through" and the mem of "them," so that the two-letter root denotes the conglomeration and meeting point of several parties. Bamah, the private altar, he derives from it as a site where many gathered in communal worship; bamah also means "high place," which many commentators take to be the word's original meaning, since such gatherings were usually held at elevated spots to be seen. Pappenheim then sets yavam against the other in-law terms: a spouse has only one father-in-law and one mother-in-law, so choten / chosenes and cham / chamos are always limited to one person, whereas marriage can bring any number of siblings-in-law at once, a kind of mass gathering of family.
• Rabbi Yaakov Tzvi Mecklenburg (1785-1865) cites Pappenheim but ultimately prefers another approach, connecting yibbum to bamah through the traditional sense of a high place: yibbum lifts up a downtrodden childless widow by marrying her and making her feel important again, or, he alternatively suggests, elevates the deceased brother's neshamah by establishing a family in his name.

What the verb yibbum does to her status.

• Rabbi Shlomo Pappenheim: at the husband's death she was no longer actively considered a sister-in-law to the surviving brothers, and one of them marrying her brings her back into the family as a yevamah to the rest, which is why the mitzvah is called yibbum.
• Rabbi Wolf Heidenheim (1757-1832) takes the exact opposite approach: yibbum does not reinstate a lost status, particularly since halachically she never stopped being a sister-in-law to her husband's brothers; rather it makes her a wife instead of a yevamah and so eliminates that status as regards him, on the pattern of shoresh, a root, against l'sharesh, to uproot.
• Ibn Ezra (Bereishis 38:8) seems to explain, alternatively, that yibbum refers not to the yevamah but to the yavam: it is the quintessential act of brother-in-lawing, the yavam acting as brothers-in-law should who take charge of a widowed sister-in-law and bring her into their own family (see also Meshech Chochmah to Devarim 25:5).

Whether yavam is a kinship word at all.

• Rabbi Mecklenburg and others, cited by Rabbi Heidenheim: Biblical Hebrew has no special word for brother-in-law or sister-in-law, the latter being eishes achiv, "his brother's wife" (Bereishis 38:8-9; Vayikra 18:16, 20:21), and only later Rabbinic Hebrew introduced giss / gissa. On their view yavam / yevamah name specifically the parties to the mitzvah of yibbum and are not general kinship terms.
• Rabbi Heidenheim himself cites Ibn Ezra and HaBachur as clearly disagreeing, taking yavam / yevamah as kinship terms even outside a yibbum context.

What giss covers.

• Rabbi Wolf Heidenheim: only a spouse's sibling or that sibling's spouse, so two men are gissim only if they married two sisters, and a man's sister's husband is not his giss even though English would call him a brother-in-law. His proof is the Mishnah (Sanhedrin 3:4), which lists the relatives disqualified from testifying and mentions baal achoso, his sister's husband, separately from gisso.
• Rabbi Tanchum HaYerushalmi, a thirteenth-century exegete who lived in Eretz Yisrael, defines giss as a man's wife's sister's husband, implying that his sister's husband is not his giss.
• Rabbi Klein holds that Heidenheim's proof from the Mishnah is not foolproof: Chullin 18b has Rabbi Yochanan calling Reish Lakish gissa gissa, which the Ritva says recalls that Reish Lakish was married to Rabbi Yochanan's sister (Bava Metzia 84a), and on that basis the Nimukei Yosef (Sanhedrin 6a in the Alfasi pagination), written by a student of the Ritva, explains that a sister's husband can evidently still be called a giss despite the Mishnah's separate listing.
• Rabbi Eliyahu HaBachur (1469-1549) cuts it by the speaker: a man calls his wife's brother a giss, a woman calls her husband's brothers her yavam, even where the mitzvah of yibbum does not apply, as when the Midrash speaks of Moshe from the standpoint of his sister-in-law Elisheva, Aharon's wife, and the Gemara (Zevachim 102a) calls him her yavam; so too two women married to brothers call each other yevamos (Rus 1:15). For HaBachur both a man's sister's husband and his wife's brother may be called giss, so two men married to two sisters are gissim; he concedes that a man might call his brother's wife or his wife's sister gisaso, but holds that a borrowed rather than the primary sense.

Whether choten can mean brother-in-law.

• Ibn Janach (990-1050) says yes, adducing it from his understanding that Chovav ben Reuel was a son of Moshe's father-in-law Yisro/Reuel (Bamidbar 10:29), while Shoftim 4:11 describes Chovav as Moshe's choten.
• Radak (1160-1234) disagrees and clarifies that Chovav is another name for Yisro and Reuel was Chovav's father, so Chovav was Moshe's father-in-law and there is no proof at all that choten can mean brother-in-law.

Rabbi Klein observes that both of them seem to disregard the Midrashic position that Reuel and Chovav are both alternate names for Yisro. There is precedent for Ibn Janach's assertion in other languages: the Akkadian cognate of choten can mean both father-in-law and brother-in-law, and in Yiddish shvugger, brother-in-law, and shver, father-in-law, ultimately derive from a shared etymon, swehuraz in proto-Germanic and swekuros in proto-Indo-European.