chewing

Distinctions

Koses / kesisah (כסס, כסיסה)

The one with the wider spread of citations. Berachos 37a: one who is koses raw wheat or rice says borei pri ha'adamah, not borei minei mezonos; the Tosefta (Berachos 4:6-7) uses the same verb for the rejected opinion of borei minei zera'im. Mishnah Nedarim 6:10 and Tosefta Nedarim 3:7 ask whether one who forswore wheat may still be lachus raw wheat. Berachos 36b and Yoma 81a use kas for chewing dry pepper or ginger on Yom Kippur, which Rava holds is not biblically "eating." Megillah 7b has Abaye so hungry he could be koses the plate.

Rashi gives two definitions.

• To Megillah 7b, Kesubos 77a, Berachos 36b, Yoma 81a and Chullin 15a: kesisah is eating in any abnormal or non-standard way. (Maharsha to Megillah 7b suggests the plate there may simply have been edible.)
• To Beitzah 26b: whatever can be eaten raw, eating it raw is koses.

Rabbi Reuven Chaim Klein calls this second one a slightly different definition.

Etymology: several philologists, among them Dr. Asher Weiser and Rabbi Yaakov Yehudah Zilberberg (Di Kasif), tie rabbinic כ-ס-ס to biblical ק-ס-ס, which occurs once, yikoses, of cutting down a metaphoric tree's fruit (Yechezkel 17:9).

• Rashi there links ק-ס-ס to ק-צ-ץ (cutting) by the samech/tzadi interchange.
• Mahari Kara links it to כ-ת-ת (smashing) by kuf/kaf and samech/tav.
• Ibn Janach and Radak take the root as triliteral.
• Menachem Ibn Saruk takes it as the biliteral ק-ס.
• Rabbi Shlomo Pappenheim (Cheshek Shlomo) implicitly follows the biliteral and defines ק-ס as "a cut tube": yikoses takes the cutting side; keses (a scribe's stylus, Yechezkel 9:2, 9:11), kesem (a magic wand, or magical writings written with a keses), and kisam (toothpick) take the tube side, tubes cut lengthwise, while the kesavos of the Shulchan (Shemos 25:29, Bamidbar 4:7) are tubes cut across their width. He includes kaskeses, the scale of a kosher fish, in the same family.

Two extensions. Kaskasa is to crunch or crush between the teeth; the piyut Elokei HaRuchos of Rabbi Yosef Tuv-Elem of Bonfils, recited in some communities on Shabbos HaGadol, requires kiskusei of the maror, which the Ohr Zarua (Hilchos Pesachim 256) reads as munching, so that one does not swallow the maror without tasting its bitterness, while Rabbi Shamshon Raphael Ortzel of Bayit Ve'Gan suggests it may instead mean vigorous shaking (as in Shulchan Aruch, Orach Chaim 651:9 for the lulav), meaning shake the charoses off first. The verb l'kaskes in Mishnah Niddah 9:7 is vigorous rubbing in laundering, which perhaps resembles chewing in its consistent forceful movement.

Rabbi Ernest Klein (no relation to Rabbi Reuven Chaim Klein) traces kesisah/koses back to the Akkadian kasasu (cutting into pieces) and kissatu (fodder), and holds them related to an Arabic cognate meaning pounding, grinding or pulverizing.

The French couscous (from the Arabic kuskus), a food of small bits of pounded grain, is also cognate with koses, since it describes chopped grains that look as though they were pre-chewed; but the English kasha (buckwheat) has no connection to it, having come by way of Yiddish from the Slavic languages, where it meant groats, cereal or porridge and not buckwheat in particular. The philologist Samuel Krauss links כ-ס-ס to ע-ס-ס (assisi, juicy), possibly because chewing a food releases its inner juices and lets one taste its flavors. And one Dr. A. Weiss (in YU's rabbinic journal Chorev, 1943, vol. 7, p. 55) claims that the kos of the rabbinic kos shel akarin, a contraceptive draught, is not kos in the sense of cup at all but a cognate of koses, the ingredients having been cut or chopped into small bits and mixed together.

Also from this root, kisnin: Targum renders the biblical nikkudim, food provisions (Yehoshua 9:5, 9:12; Melachim I 14:3), as kasnin, and the halachic pas haba'ah b'kisnin (Berachos 42a) uses the same word.

• Radak (to Melachim I 14:3) relates kisnin to koses: they are the sorts of treats one munches at a party or a wedding. Comparable definitions are cited in the name of Rabbeinu Chananel (Ohr Zarua, Hilchos Berachos 149) and Rav Hai Gaon (Sefer HaNer to Berachos 42a).
• Rabbi Moshe Tedeschi-Ashkenazi (Hoil Moshe to Melachim I 14:3) suggests a different tie to koses, since kisnin are a food that crumbles into small pieces.

Lo'es / le'isah (לעס, לעיסה)

Three times in the Mishnah. Shabbos 19:2: if cumin was not ground before Shabbos one may chew (lo'es) it whole for the milah dressing. Niddah 9:7: chewing grits for a cleaning agent against blood stains. Pesachim 2:7: one may not chew (lo'es) wheat on Pesach for a wound dressing, since it will become chametz. Berachos 44b: spleen is good for the teeth and bad for the bowels, so chew it and spit it out, again with lo'es.

Rashi twice defines it by the other word, to Pesachim 39b and to Berachos 44b: lo'es is koses. The root ל-ע-ס is Aramaic and Syriac for chewing and appears in Targum (to Koheles 12:3); beyond that its origin is obscure.

• Rabbi Moshe Tedeschi-Ashkenazi (Otzar Nirdafim) explains mitalot, the molars that grind food right before one swallows, as a fusion of the biliterals ת-ל, hanging, and ל-ע, swallowing; he notes an affinity between that root and ל-ע-ט, to guzzle or gulp (haliteini, Bereishis 25:30, as his teacher Shadal notes there; malitin, force-feed, Mishnah Shabbos 24:3), and relates these roots as well to ל-ע-ס.
• Rabbi Avi Kobernick (Hipuch Otiyos) offers a speculative metathesis of ס-ל-ע, rock: a sela is what will not break down, and lo'es is precisely breaking down.

Are they synonyms?

Rabbi Reuven Chaim Klein's own suggestion is that perhaps the two need no semantic difference at all, since they appear to be of different origins: koses seems to be a native Hebrew word, lo'es seems to be a loanword from Aramaic, so their overlap would not be superfluity.

Members of the Mazuz family of Tunisia seem to presume a real difference, though Rabbi Reuven Chaim Klein grants that it is hard to substantiate and hard even to say exactly what it means.

• Rabbi Matzliach Mazuz (Ish Matzliach vol. 2, Orach Chaim 47), discussing at length whether pilpel is the common pepper, black pepper, or both, raises how the use of kas rather than lo'es for chewing pilpel on a fast day might bear on that question.
• Rabbi Meir Mazuz (Arim Nissi to Pesachim 39b): le'isah typically implies chewing as part of eating, in preparation for swallowing, while kesisah does not necessarily bear that implication; that is why Rashi glosses lo'es as koses in the case of chewing wheat for a bandage, to say that this man was not chewing in order to swallow but only to soften the grain.
• Rabbi Yitzchak Barda (a son-in-law of Rabbi Matzliach Mazuz) notes that the Rema (Orach Chaim 567:3, following the Tur) permits lo'es of cinnamon sticks and other unpulverized spices on a fast day other than Yom Kippur, to wet the throat, provided one spits it out, while his source, the Ravyah (Hilchos Taanis 861), writes lachus; he explains kesisah as the chewing with more enjoyment of the spices' sweet juices than le'isah implies. Rabbi Klein glosses that as kesisah possibly connoting forceful or even indulgent mastication and le'isah leaning toward a more utilitarian chewing, but that gloss is his own paraphrase of Rabbi Barda.

Sources

Rabbi Reuven Chaim Klein, "Behaaloscha: Chew That," What's in a Word?, Ohr Somayach, 14 June 2025.

Rabbi Reuven Chaim Klein, "Showing Teeth," What's in a Word?, Ohr Somayach, 22 April 2023.

Cited in the essay: Bereishis 25:30 with Shadal; Bamidbar 4:7, 11:33; Shemos 25:29; Vayikra 11:3-7 and Devarim 14:6-8; Yehoshua 9:5, 9:12; Melachim I 14:3 with Radak and Hoil Moshe; Yechezkel 9:2, 9:11, 17:9 with Rashi and Mahari Kara; Koheles 12:3 in Targum; Berachos 36b, 37a, 42a, 44b; Tosefta Berachos 4:6-7; Mishnah Nedarim 6:10 and Tosefta Nedarim 3:7; Yoma 81a; Megillah 7b with Rashi and Maharsha; Kesubos 77a with Rashi; Beitzah 26b with Rashi; Chullin 15a; Mishnah Shabbos 19:2 and 24:3, Niddah 9:7, Pesachim 2:7 with Rashi to Pesachim 39b; Rabbi Shlomo Pappenheim, Cheshek Shlomo s.v. ק-ס; the piyut Elokei HaRuchos; Ohr Zarua, Hilchos Pesachim 256 and Hilchos Berachos 149; Sefer HaNer to Berachos 42a; Shulchan Aruch, Orach Chaim 567:3 with the Ravyah, Hilchos Taanis 861, and 651:9; Ish Matzliach vol. 2 Orach Chaim 47; Arim Nissi to Pesachim 39b; Rabbi Avi Kobernick, Hipuch Otiyos; Rabbi Moshe Tedeschi-Ashkenazi, Otzar Nirdafim; Rabbi Yaakov Yehudah Zilberberg, Di Kasif; Dr. Asher Weiser, Mikra V'Lashon (עמ' 249); Rabbi Ernest Klein; Samuel Krauss; Dr. A. Weiss, Chorev 1943 vol. 7 p. 55.