in-laws

Distinctions

Cham (חם) and chamos (חמות)

The wife's words. Yehudah is called Tamar's cham (Bereishis 38:13, 38:25), and Naomi is Rus's chamos (Rus 2:11 through 3:17).

• Rav Hirsch: in a traditional patriarchal society, where marriage is viewed as a woman leaving her parents' family and joining her husband's, his relatives stand around her like a chomah, a wall; hence cham and chamos.
• Rabbi Shlomo Pappenheim reads the same letters as the biliteral ח-ם, hot: a bride must stress the warm love she receives from her new relatives in order to honor her husband, and love is spoken of metaphorically as fire (Shir HaShirim 8:7), so it makes sense that she names them from the root of heat.
• The kabbalist Rabbi Menachem Azariah of Fano: the husband's parents do not give their son in the way the wife's parents give their daughter; their contribution is that they gave birth to him, so the words derive from yechemasni ("birth," Tehillim 51:7).

The Pri Megadim (Rabbi Yosef Teomim-Frankel), in a letter on dikduk, suggests working from the Aramaic instead: ח-ם there means "to see," and the Targumim always render Hebrew chosen/choseness with cognates of cham/chamos. A woman's mother-in-law is chamos because she is forever watching her daughter-in-law, for good or otherwise (Yevamos 15:4 presumes that the two are always assumed to hate each other). From the mother-in-law's title the matching word for the wife's father-in-law was formed, and from there the pair spread to a husband's in-laws as well.

Ibn Janach (s.v. חמה): chamos, mother-in-law, is related to cheimah, anger.

Chosen (חותן) and choseness (חותנת)

The husband's words, and cognate with chasan. Yisro is called Moshe's chosen thirteen times in Shemos 18:1-27, and the curse on incest with a mother-in-law reads shochev im chosanto (Devarim 27:23).

• Rav Hirsch: the husband does not join a new family; his family forms a connection with another family while he remains in his own, so his words for his in-laws are built on connection, like chasan. (Hebrew and Yiddish have mechutanim for two people whose children have married each other; English has no word for that relationship at all.)
• Rabbi Shlomo Pappenheim derives chasan from the biliteral ח-ת, descending or setting down, since the groom branches off from his family to found a new subdivision; his parents-in-law are chosen and choseness because in giving him their daughter they gave him the chance to open that branch. (Radak gives the core sense of chasan differently, as one who experiences a new joy, which is why the word covers a baby at his bris as well as a groom.)
• Rabbi Menachem Azariah of Fano reads chosen as a contraction of achos nosen, "a sister he gives," on the premise that soulmates stand on a level and a husband and wife may be called brother and sister; the father-in-law is the one who gave this man his "sister," which is why the word can only ever be the husband's.
• Rabbi Yonah Ibn Janach: chosen, usually father-in-law, can also mean brother-in-law, since he takes Chovav ben Reuel as a son of Moshe's father-in-law Yisro/Reuel (Bamidbar 10:29), and Chovav is called Moshe's chosen (Shoftim 4:11). Radak disagrees: Chovav is another name for Yisro and Reuel was his father, so Chovav was Moshe's father-in-law and there is no proof. Both seem to disregard the Midrashic position that Reuel and Chovav are alike alternate names for Yisro. The Akkadian cognate of chosen can mean both father-in-law and brother-in-law.
• Rabbi Eliyahu Benamozegh (Eim LaMikra to Shemos 2:18) widens it further: chasan and chosen name any relationship made by marriage, and with this he settles the contradiction over Athaliah's parentage. On that basis Reuel was Moshe's father-in-law, and Yisro and Chovav were Reuel's two sons. When Reuel died, Yisro took his place as head of the tribe, perhaps as the eldest son, which is why Moshe tended his flock (Shemos 3:1); and in the second year after the Exodus, Chovav joined the Jewish People.

Pri Megadim on why this pair never widened: chosen names the man who made him a chasan, and choseness was formed from it. Since chasan is by definition the husband's standpoint, the pair cannot be turned around to the wife's, even in Mishnaic Hebrew.

The Mishnaic widening

Radak notes that in Mishnaic Hebrew cham is already used of a husband's father-in-law (Kesubos 1:5) and chamos of a husband's mother-in-law (Yevamos 1:1). Rabbi Shimon Pollack (responsa Shem MiShimon), asked why a man says avi mori of his father but mori vechami of his father-in-law, putting "my teacher" first in the second, offers as one suggestion that chami in that sense is only Mishnaic and rests on Aramaic, so the Hebrew mori is given precedence; whereas for one's father both words are Hebrew. He supports this from the fact that a man who uses the Biblical chosni will usually say chosni mori, both words there being Hebrew. Rabbi Klein explains the switch simply by the order of events: a man's father was first his father and only then his rebbe, hence avi mori; and usually, where a man says mori vechami, the one he names became his father-in-law because he was first his rebbe.

Sources

Rabbi Reuven Chaim Klein, "Heat with the In-Laws," What's in a Word?, Ohr Somayach, 15 February 2020.

Rabbi Reuven Chaim Klein, "Sort of Siblings," What's in a Word?, Ohr Somayach, 21 August 2021.

Rabbi Reuven Chaim Klein, "Heat with the In-laws," What's in a Word? Synonyms in the Hebrew Language (book manuscript).

Rabbi Reuven Chaim Klein, "G-d’s Best Friend," What's in a Word? Synonyms in the Hebrew Language (book manuscript).

Cited in the essay: Shemos 18:1-27; Devarim 27:23; Bamidbar 10:29; Shoftim 4:11; Ibn Janach; Bereishis 38:13, 38:25; Rus 2:11-3:17; Shir HaShirim 8:7; Tehillim 51:7; Kesubos 1:5; Yevamos 1:1 and 15:4; Radak, Sefer HaShorashim; Rav Hirsch; Rabbi Shlomo Pappenheim, Cheshek Shlomo s.v. חם, חת; Rabbi Menachem Azariah of Fano; the Pri Megadim, in a letter on dikduk; Shem MiShimon (Rabbi Shimon Pollack); Ibn Janach, Sefer HaShorashim s.v. חמה; Shemos 2:18 with Benamozegh; Shemos 3:1.