God goes by many names in the Bible, but he only has one personal name, spelled using four letters - YHWH. It truly has become an ineffable name: we know neither how it was pronounced in antiquity, or what it meant.
The practical reason for the mystery of its original pronunciation is that Hebrew is written without vowels. Technically, almost any combination of vowel sounds could have been used with those consonants, thus many different pronunciations are possible.
The other reason is more spiritual. The pronunciation of other biblical words were meticulously preserved for us by an unbroken chain of tradition passed on orally from generation to generation, until eventually it was put down in writing in Tiberias in the 10th century C.E. by Aaron ben Moses ben Asher, who refined the system of diacritic marks that Hebrew still uses to indicate vowel sounds.
But, this was not the case with the name of God.
This may seem odd. Why would the Jews preserve the pronunciation of all other words in the Bible but neglect to preserve the pronunciation of the one most important word, which appears in the Bible some 6,600 times - the name of God himself?
The reason is that during the Second Temple period, most likely in the early 5th century B.C.E., Jews decided that that name was ineffable, too holy to be uttered aloud. This was based on a particular interpretation of the third commandment, “Thou shalt not take the name of the Lord thy God in vain.”
The commandment probably intended, at its origin, merely to prohibit inappropriate invocation of God’s name, when swearing and the like, but during this time it began to be viewed as a prohibition against uttering the name in all but the most solemn of circumstances.
According to the Mishnah (redacted in 200 C.E. but containing ancient traditions going back hundreds of years), the sacred name was only to be pronounced in the Temple in Jerusalem, and only in very specific occasions - by the High Priest on Yom Kippur and when the priests sanctified the crowds with the Priestly Blessing.
When the Temple in Jerusalem was destroyed in 70 C.E. by Rome, to punish the Jews for their latest rebellion, there was no longer any context in which the uttering of God’s name was permissible. Since then, to this day, when the name YHWH arises during prayer or recitation outside the Temple, Jews read it aloud as 'adonai, meaning “my lord.” Thus the true pronunciation was eventually lost.
Still, linguists and biblical scholars have come up with a likely reconstruction based on ancient transcriptions, information gleaned from theophoric names, comparative material, and Hebrew grammar. The details of these analyses are too technical and frankly boring to even summarize here, but the upshot is that in all likelihood, in biblical times, the name was pronounced yah-weh, with soft a and soft (and slightly elongated) e.
The meaning of YHWH
Moving on from its missing pronunciation, what did the name YHWH mean?
Hebrew words, or words of any other Semitic language, usually have three-letter roots. Analysis of Semitic words starts with that trilateral root, which appears in other words with related meanings.
This is, at a very basic level, how Hebrew and other Semitic languages work. The root has a basic meaning, which gains specific meanings with the addition of other sounds (consonants and vowels).
Take for instance the root SRK: masrek means comb, lehistarek means to comb (one's hair), saruk is the passive past tense, combed; srika means medical scan - combing through your innards, and so on.
In the case of god, the trilateral root seems to be HWH.
If this is true, and it probably is, the root HWH is likely a variant of the very common Hebrew root HYH. It is very common in Hebrew for W and Y to interchange. HYH simply means “being.”
Also, the format of the name YHWH is similar to that of causative verbs, verbs that indicate the subject is causing a change in the verb’s object, such as English’s spill or hire. So, if we accept the root as HWH or HYH, and assume it has causative structure - taken together, the name seems to mean “bring into being.” Or, “creator.”
This interpretation is supported to a certain extent by the Bible itself.
Who are you?
When God reveals himself to Moses in a burning bush (Exodus 3), Moses asks him what his name is.
"Behold, when I come unto the children of Israel, and shall say unto them, The God of your fathers hath sent me unto you; and they shall say to me, What is his name? what shall I say unto them?"
God answers “I Am that I Am," and adds,
"Thus shalt thou say unto the children of Israel, I Am hath sent me unto you.”
That “I am” repeated three times in this verse is ehyeh – again, from the root that means "being."
This means that at least the person who wrote this story understood God’s name to be related to "being".
Still, not all scholars accept this etymology. And there have been many other proposals.
According to one very unlikely theory, the name is not Semitic in origin at all - it stems from the same proto-Indo-European word for god that gave Latin "Jupiter" and Greek "Zeus."
Somewhat more probable is the theory that connects YHWH with the Arabic verb haw, meaning “blow,” which would be fitting for a storm god; or the theory that the name arises from a hypothetical Ugaritic root HWY, which might have carried the meaning “speak.”
Yet another theory has it that the name was formed from two Arabic words: ya, a short word used to indicate you are talking to a person (e.g., you tack it on before a name of a person you are addressing – as in "Ya George, light the fire") and huwa, meaning, "he."
Whatever the name's meaning and however it was pronounced in the past, today the word itself is rarely written in Hebrew outside scripture and prayer. Modern written references to the deity in Hebrew take various forms and abbreviations. The most common is ה׳.
However written, the name of God is considered so holy that once it appears on a page, it may not be erased, nor may the page be destroyed or thrown out in the trash. It must be deposited in a special synagogue archive called a genizah, or buried in a cemetery.
Meanwhile, as we said, we lost the original pronunciation of God's name because it is too holy to say aloud. But nowadays, even the euphemism used in its stead, adonai, is considered too holy to be uttered outside of a liturgical setting. So new euphemisms have arisen, the most common being: hakadosh baruch hu (“the holy one blessed be he”) and hashem (“the name”). Whatever that name may be.