From its humble beginnings as a Roman numeral to its eventual tenth position in the English alphabet, J has had quite a linguistic journey.
When was J added to the alphabet?
J is a bit of a late bloomer; after all, it was the last letter added to the alphabet. It is no coincidence that I and J stand side by side—they actually started out as the same character. The letter J began as a swash, a typographical embellishment for the already existing I. With the introduction of lowercase letters to the Roman numeric system, J was commonly used to denote the conclusion of a series of ones—as in “xiij” for the number 13.
(A story for another day: the name of the dot over the “j” and “i,” and why we use them.)
Are J and I related?
J’s phonetic quest for independence probably began with the sound of the letter I. Originally a Phoenician pictogram representing a leg with a hand, and denoting a sound similar to the Y in “yes,” I was later adopted by Semitic groups to describe the word “arm” which, in Semitic languages, began with a J (also possessing the same Y sound as in “yes”).
How did J get its sound?
Both I and J were used interchangeably by scribes to express the sound of both the vowel and the consonant. It wasn’t until 1524 when Gian Giorgio Trissino, an Italian Renaissance grammarian known as the father of the letter J, made a clear distinction between the two sounds. Trissino’s contribution is important because once he distinguished the soft J sound, as in “jam” (probably a loan sound), he was able to identify the Greek “Iesus” a translation of the Hebrew “Yeshua,” as the Modern English “Jesus.” Thus the current phoneme for J was born. It always goes back to Jesus.
The English language is infamous for matching similar phonemes with different letters and J is certainly no exception. In addition to the aforementioned soft J sound, as in “jam,” which is phonetically identical to the soft G as in “general,” the J in Taj Mahal takes on a slight variation of that same sound and is probably the closest to Trissino’s original phonetic interpretation. And, coming full circle, the J sound you hear in the word “hallelujah” is pronounced “halleluyah.”