geves and gypsum

The Hebrew word geves גבס and the English word gypsum are closely related. Let's see how.

In Hebrew today, you'll most likely hear geves used to describe a type of construction - drywall, used to form the interior walls of buildings, and for orthopedic casts of plaster. But both of those uses were adopted because of the mineral primarily used to make them - gypsum.

During Talmudic times there were a number of longer words for gypsum including gipsis גפסיס (Para 5:9, Pesachim 75a), gipsos גיפסוס (Yerushalmi Shabbat 5:1) and gipsim גפסים (some versions of Kelim 10:2). The Ben Yehuda dictionary reports that the current form, geves, was based on these Talmudic forms, and this was the word used by people in Eretz Yisrael in his time. He doesn't mention this, but I wonder if perhaps the switch from the letter "pe" to the letter "bet" was due to influence from contemporary Arabic, who often make that switch, and pronounce their word for gypsum as jabas. (It's possibly that the answer is in page 119 of this book, but unfortunately I don't have access to it and  Google Books only gives me a snippet view.)

The dictionary also points out that the Talmudic forms come from the Greek, and this is where the English word gypsum derives as well. Klein writes in his CEDEL in the entry for "gypsum":

Latin, from Greek gypsos, 'chalk', of Semitic origin. Compare Arabic jibs, Mishnaic Hebrew gebhes, gephes, 'plaster, mortar, gypsum', which probably derive from Akkadian gassu (whence also Aramaic gassa גצא, whence Arabic jass, jiss, juss, qass, qiss), 'gypsum'.

The Aramaic gatza גצא, which according to Sokoloff means "lime", is found in some Talmudic era texts (some versions of Moed Katan 10b) as a parallel to sid סיד - "whitewash".

So as often happened in that region, the word geves was originally Semitic (Akkadian), then borrowed into Greek, then borrowed back into Hebrew and Aramaic. That is how language is built - not with stone walls that never change, but with much more adaptable gypsum...