Take those people who think that every word in English comes directly or indirectly from Hebrew, because Hebrew must be the first language. What worldview do they have in which their foundations of faith crumble if Hebrew was not the very first language? Do they really believe what they say, or do they say it because they need to think it's true for some reason? Do they think that Hebrew being some kind of primal language makes it more "authentic" or superior? Fascinating. Don't you think?
(Mar)Cheshvan is a terrific month for thinking about folk etymology. Anyone who grew up going to Jewish day school probably learned at a young age that the Hebrew month of Cheshvan is sometimes called "Marcheshvan" because it is a "bitter" (Hebrew: "mar") month due to its lack of holidays. I think I might have even been taught (or derived myself) that it was the only holiday-less month, despite the fact that Iyar, Tammuz, Elul, and Tevet are also apparently holiday-less. Av is no great shakes, either, and would be a prime candidate for a "bitter" month in my book, although I suppose the bitter lamentations of Tisha B'Av are mediated somewhat by Tu B'Av.
The actual etymology of "Marcheshvan" is apparently the Akkadian word "waraḫsamnu," meaning "eighth month." (Waraḫ presumably being like the Hebrew "yare'ach" or moon and samnu presumably being like the Hebrew "shmona" or eight. How's that for some amateur etymology?) Indeed, in the biblical account of the months, Marcheshvan is the eighth month. The real question is not why Cheshvan is called Marcheshvan, but why it is called Cheshvan without the "Mar." Who dropped the "mar" and why?
But the etymology doesn't stop there. Oh, no!
In the Bible, the eighth month is referred to by name only once, and is called "Bul." This is in I Kings 6:38, where it describes King Solomon's completion of the Temple in Jerusalem:
|לח ובשנה האחת עשרה בירח בול, הוא החודש השמיני, כלה הבית, לכל-דבריו ולכל-משפטיו; ויבנהו, שבע שנים||38 And in the eleventh year, in the month Bul, which is the eighth month, was the house finished throughout all the parts thereof, and according to all the fashion of it. So was he seven years in building it.|
Rashi explains that "bul" means "mabul" ("flood"), because this is the month during which the Great Flood (with Noah and the ark and all that) occurred. Rashi might have given this explanation (bul = mabul) because Cheshvan/Bul is the month during which a special prayer for rain is added in the land of Israel, and during which if there is no rain, special fasts were instituted to pray for rain. But does "Bul" really come from the word "mabul"? Maybe it does, in which case this not a folk etymology by a real etymology.
Either way, have a sweet Cheshvan!