On Shavuot we celebrate the giving of the Torah at Sinai, and read the Ten Commandments. Or do we?
First of all, the "Ten Commandments" is not a good translation. As Philologos wrote:
Let's start with No. 1. What is called "The Ten Commandments" in English and other European languages, a phrase translated from the Latin Decem Mandati, is known in Hebrew as Aseret Ha-dibrot, "the ten dibrot." A diber (singular of dibrot) is not a mandatus or commandment; rather - a noun deriving from the verb daber, to speak - it means an act of speech or an utterance, as in the verse in Jeremiah, "And the prophets shall become wind and the utterance [diber] is not in them." The Aseret Ha-dibrot in Jewish tradition are thus "The Ten Utterances," not "The Ten Commandments."
Why is the singular of dibrot דברות diber דיבר? Dr. Eliyahu Netanel explained in his column, Lashon Limudim, in Shabbat B'Shabbato, Bamidbar 5766. He writes that diber is masculine, and the plural is dibrot (which appears feminine) and this is similar to kise כסא and kisaot כסאות - chairs. Here's a list of many more, and an explanation to the phenomenon.
Netanel also writes that where the term diber was used in Eretz Yisrael, in Bavel they would say dibur דיבור. This helps to explain a midrashic saying (Shvuot 20b; it also appears in the song Lecha Dodi) - שמור וזכור בדיבור אחד - shamor v'zachor b'dibur echad. This refers to the fact that the fourth diber - the mitzva of shabbat - appears with the word shamor in Sefer Shmot and zachor in Sefer Devarim. Generally, it is assumed that this means that they were spoken - dibbur - at the same time. But if dibur is the Bavli term for diber, than it means they were in the same fourth diber- also miraculous, according to the midrash, but a slightly different understanding.
However, if we go back even further, we see that in the Torah itself (Shmot 34:28, Devarim 4:13, Devarim 10:4), they weren't called aseret hadibrot, but עשרת הדברים aseret hadvarim. This leads some to think that the Greek term decalogue - "ten statements" or "ten words" - is the most accurate option for use in English.