If you haven't noticed, my recent posts have frequently referred to Klein's Comprehensive Etymological Dictionary of the English Language (CEDEL). I purchased the two volume set a few years ago, but recently decided that if I want to find the cases where he provides Semitic origins to English words, I'd have to just start reading it from the beginning. And that's what I've been doing for the past few weeks. It will probably take me several months to complete the project.
I can't say that every entry with a connection to Hebrew is entirely convincing, but I can say that Klein does seem to be doing his best with the tools he had, and often provides sources, which makes follow up research much easier.
One interesting aspect of this project has been noticing when the Online Etymology Dictionary (Etymonline), a very popular internet etymology resource (which I quote often), relies on the CEDEL for an etymology, but won't go the final mile and mention the Hebrew cognate that Klein suggests.
An example of this can be found in the entry for "cedar" and related words. Etymonline has the following entry for cedar:
"type of coniferous tree noted for its slow growth and hard timber," late Old English ceder, blended in Middle English with Old French cedre, both from Latin cedrus, from Greek kedros "cedar, juniper," a word of uncertain origin.
After mentioning the Middle English, Old English, French, Latin and Greek origins (as also done by Etymonline), Klein continues:
which probably denoted originally 'a tree whose wood was used for burning sacrifices,' and derives from Hebrew qatar, 'it exhaled odor, smoked'; see Heinrich Lewy, Die semitischen Fremdwörter im Griechischen, Berlin, 1895, p. 35.
We discussed qatar in a post about the etymology of "nectar", and its relationship to ketoret. But I wasn't familiar at the time with the possible connection to "cedar," so I didn't mention it then.
At the end of that entry, Klein recommends also looking at his entry for "citron" (the English name for the etrog tree and fruit.) He connects "citron" to "cedar", and then mentions that "citrus" comes from "citron" as well. Here Etymonline does make direct mention of Klein. Here's their entry for citrus:
any tree of the genus Citrus, or its fruit, 1825, from the Modern Latin genus name, from Latin citrus "citron tree," the name of an African tree with aromatic wood and lemon-like fruit, the first citrus fruit to become available in the West. The name, like the tree, is probably of Asiatic origin [OED] or from a lost non-IE Mediterranean language [de Vaan]. But Klein and others trace it to Greek kedros "cedar," perhaps via Etruscan (a suggested by the change of -dr- to -tr-).
And their entry for citron is connected:
"large, thick-rinded, lemon-like citrus fruit," late 14c., also citrine (early 15c.), from Old French citron "citron, lemon" (14c.), possibly from Old Provençal citron, from Latin citrus "citron-tree," and influenced by lemon; or else from augmentative of Latin citreum (mālum) "citron (apple);" see citrus.
To be clear, I don't object to Etymonline disagreeing with Klein's conclusions. I just think it would be easier for future investigations if they were quoted more inclusively.
One remaining question is what is the connection between the cedar and citron trees? In Italian the same word - cedro - is used for both, so certainly some association is possible. This book quotes Galen (the Greek physician living in the Roman empire) who provided a few possible theories:
because the green unripe citron resembles the unripe cedar-cone; or because cedar and citron trees have spines around the leaves [...] or more fancifully because the the fruit and leaves had the smell of cedar...
(Regarding the first theory, there are those who claim that when the Bible refers to pri etz hadar פרי עץ הדר, it did not mean the etrog / citron, but rather the cedar cone. Others reject this, because the cedar tree has a common name in the Bible, erez ארז and no connection is made between erez and hadar in any biblical text.)
While all of Galen's theories may be a possible connections between cedar and citron, if we rely upon Klein's etymology for cedar, which goes back to the odor from the tree, then perhaps the citron tree was similarly named for its strong aroma. While the cedar may have got its name from the odor when the wood was burned, certainly anyone who has smelled a citron can attest to its powerful scent as well.