The Hebrew language is seemingly blessed with three different words that mean marsh or swamp. When Pharaoh saw a dream consisting of seven fat cows, the Bible (Genesis 41:2 and 41:18) reports that those cows were grazing in an achu (marsh).
Yet, to start the plague of blood, G-d told Moses to tell Aaron to stretch his hand “over the waters of Egypt – over their rivers, over their canals, over their marshes (agam), and over all their gatherings of water” (Exodus 7:19; see also ibid., 8:1).
“Bitzah,” a third word for marsh, appears three times in the Bible (Job 8:11 and 40:21 and Ezekiel 47:11).
Rashi (to Genesis 41:2) asserts that “achu” means “agam.” To support this claim, Rashi cites Job 8:11, which reads: “Can reeds (go’me) grow tall without a marshland (bitzah), or a marsh (achu) without water?”
But Nachmanides (to Genesis 41:2) argues that “achu” does not mean marsh, but rather a certain type of grass or vegetation that tends to grow on river banks. Nachmanides suggests that “achu” is related to “ach” (brother), an allusion to the comradery between various types of flora that grow in tandem along a river’s edge. (Rabbi Samson Raphael Hirsch makes the same point.)
Rabbi Pappenheim writes that “achu” refers to the brotherhood between the different animals that join up in fertile land to feast on its produce. Alternatively, an achu’s location alongside a river makes it appear as if it were the river’s brother.
Rabbi Moshe ben Shem Tov Gabbai (1340-1420) defends Rashi’s position by explaining that “achu” refers to a marsh in which the type of vegetation mentioned by Nachmanides often sprouts. Because such vegetation tends to materialize in swampy areas, the word for it became synonymous with marshes themselves such that in practice “achu” means the same thing as “agam.”
Similarly Ibn Janach and Radak’s Sefer HaShorashim propose that “achu” refers to both a certain type of grass (possibly papyrus) and the place in which that grass typically grows.
To make things a bit more complicated, Rashi (to Exodus 7:19) also defines “agam” as a stagnant body of water and translates the Hebrew word into the Old French “estanc” (“etang” in Modern French), which means pond. A pond is not quite the same thing as a marsh or swamp.
Rabbi Shlomo Pappenheim of Breslau (1740-1814) traces “agam” to the biliteral root gimmel-mem, which refers to spongy or absorbent material. In that sense, “agam” refers to a tract of water-soaked land inundated or partially flooded with water. Such a place must be sponge-like if it is to soak up so much water and always remain wet.
Another word derived from this root is “go’me,” which is a sort of spongy reed that grows in marshy wetlands. (Rabbi Wertheimer writes that a marsh is actually called “agam” because of the “go’me” that grows in it.)
The word “bitzah” derives from the Biblical Hebrew “botz” (mud, Jeremiah 38:22). Rabbi Pappenheim argues that these two words derive from the biliteral root bet-tzadi, which refers to a fluid with mucus-like consistency. The most obvious and common derivative of this root is “beitzah” (egg) whose contents are typically gooey, like mucus.
The viscosity of mud similarly resembles mucus because it is not quite as pourable as water nor can it be described as wholly solid. “Bitzah” in the sense of marsh also fits this core meaning because under swamp conditions, the ground tends to remain muddy and thus viscous. Interestingly, Rabbi Pappenheim asserts that “butz” (Esther 1:6 and 8:15 and Ezekiel 27:16) refers specifically to a type of flax/linen that grows in watery soil like that of a “bitzah.”
Rashi (to Genesis 41:2) writes that “achu” translates into Old French as “maresc” (a cognate of the English word “marsh”). Elsewhere (to Taanis 22a, Yevamos 121a, and Sanhedrin 5b), Rashi writes the same about “agam” and its Aramaic cognate “agama,” and yet again (to Ezekiel 47:11, Job 8:11, and Bava Metzia 74a), he uses this Old French word as a translation for “bitzah.”
(In this article, we used the English words “marsh” and “swamp” interchangeably. Interestingly, according to Google Books’ Ngram Viewer, “marsh” was more popular in English literature published between 1800-1850, while “swamp” was more popular from 1850-1970, then “marsh” became more popular from 1970-2000, and since 2000, “swamp” has been more popular.)