I find the etymology here very interesting.
According to Wiktionary the words meaning lemon in some IE languages like French citron or Polish cytryna originated from Latin citrus which in turn comes "probably via Etruscan from Ancient Greek κέδρος."
Words like this one in Greek, English lemon or Spanish limón which is another common name for a lemon originated "from Persian لیمو (līmū), cognate with Sanskrit निम्बू (nimbū, “lime”).
I could find very little about the etymology of κίτρινο. How are κίτρινο and citrus/citron related? Maybe κίτρινο is somehow related with that κέδρος?
Does someone know anything more about it or can google it more in Greek?
I had a quick look in the Etymological Dictionary by Γ. Μπαμπινιώτης, the Dictionary of Ancient Greek by Ι. Σταματάκος, and in the Greek and English Wikipedia. If I understand correctly the Greeks of the Hellenistic Period (ca. 323 to 30 BC) did not know the lemon (Citrus × limon), but only the citron (Citrus medica - a different fruit, see the English Wikipedia), which they called το μηδικόν μήλον ("the Median apple/apple of the Medes") or το κίτρον, the latter being a loanword from the Romans (and consequently probably a reborrowing of the Ancient Greek word κέδρος). Κίτρινος is anything that has the color of the κίτρον. [It is noteworthy that the lemon seems "to be hybrid between bitter orange (sour orange) and citron" (Wikipedia).]
A possible etymological development of κίτρον:
Hebrew and Amharic/Syriac root #ḳṭr קטר "drip" > Hebrew and Amharic/Syriac ḳiṭer קטר "incense, resin burnt for incense" > Ancient Greek κέδρος, first "juniper", later "cedar", because of their aromatic woods, possibly they where used as incense as well > possible unknown Etruscan intermediate > Latin citrus "the tree Tetraclinis articulata" (also known as Thuja articulata, sandarac, and sandarac tree) and citrium "Thyine wood, the wood of the sandarac tree" > malum citrium "citron" (malum meaning "apple" - compare μηδικόν μήλον, "apple of the Medes"), possibly because juniper, cedar, sandarac tree, and the citron were all used as insect repellents, or in general because of their aromatic qualities > Hellenistic Greek κίτρον "citron".
There is of course a certain amount of speculation involved, especially the further back in time. Most sources actually consider the origin of κέδρος to be unknown, and according to the DWDS (Digital Lexicon of the German Language) there is a possibility that Latin citrus does not come from Greek κέδρος, but that both rather have a common ancestor.
Here are my main sources:
(I do not speak Turkish, so please correct me if necessary.) http://vasco-caucasian.blogspot.com/2014/07/greek-kedros-cedar-latin-citrus-thuja.html?m=1 http://starling.rinet.ru/cgi-bin/response.cgi?single=1&basename=/data/semham/semet&text_number=3078&root=config
In an effort to help on this interesting question: There's a discussion of this matter in R. Duval & M. Berthelot, Histoire des sciences, La chimie au moyen Age, vol 2: L'alchimie syriaque.... (Paris, 1893) 12:16; 271:9 [p. 663]: https://gallica.bnf.fr/ark:/12148/bpt6k54521558.texteImage According to Brockelmann-Sokoloff Lexicon of Syriac: ܩܛܪܝܢ comes from κίτριον, which is not startling news but indicates the Syriac lexeme would seem to come through Greek. Gk κέδρος, "cedar," seems unrelated, as they were known for their great height, as in the Cedars of Lebanon, but that's just a hunch. I was surprised to read a connection to Syriac qṭr about which see the entries at the Comprehensive Aramaic Lexicon project: http://cal.huc.edu/ (there are two roots that require disambiguation). As you indicate, most people think Latin citrium is the source.
After σαν you may use the definite of indefinite article, or no article at all:
- Κίτρινο σαν το λεμόνι
- Κίτρινο σαν ένα λεμόνι
- Κίτρινο σαν λεμόνι
are all correct.
After όπως you must use an article, definite or indefinite:
- Κίτρινο όπως το λεμόνι
- Κίτρινο όπως ένα λεμόνι
are both correct, but:
- Κίτρινο όπως λεμόνι - wrong
Apart from that, the two words both mean "like" (=similar to)