I am having some trouble understanding the relationship between these three letters, which seem to get a little jumbled between the various Semitic languages. Here is what I understand, and if I'm wrong, please correct me: Hebrew "shin" seems to be etymologically equated with Arabic "sin" in that words with the "sin" radical in Arabic will usually have the "shin" radical in Hebrew. Sometimes however in words like "Israel" the "shin" letter becomes "sin" (by positioning a dot over one of the 'teeth' of the letter), which seems to be etymologically equated to Arabic's "shin" in most cases. These letters also look the same, having three teeth pointing upwards. According to "Ancient languages of Syria-Palestine and Northern Arabia", when the Hebrews adopted the Phoenician alphabet, it did not contain enough letters for all of their letters, and so that's how sin/shin converged. Then there is samek(h), which I don't understand at all. It's sound today in Hebrew seems to be the same as "sin" in Arabic, and even words like "salam" I've seen translated into Hebrew as "samek, lam, alef, meem". Was it different in the past? Because it would seem to just be the same as "sin". Any light shed on the confusion I seem to having here would be good.