Taken from the book, SACRED ORIGINS OF PROFOUND THINGS, The Stories Behind the Rites and Rituals of the Worlds Religions, by Charles Panati, 1996
"JEHOVAH" AS A CORRUPTION OF YAHWEH:
SIXTEENTH CENTURY C.E.
The Jewish Masorete scribes, who labored from the sixth to the tenth centuries C.E. to reproduce the correct Hebrew text of their Bible, the Tanakh (which has the same material as the Christian Old Testament but presents it in a slightly different order), combined the unpronounceable YHWH with vowels from two popular old Hebrew terms for God: Adonai and Elohim --- arriving at YeHoWaH, which Renaissance Christians rendered as Jehovah. This form made its way into the King James Bible.
Had the word "Yahweh" been spoken before Moses heard it on Mount Sinai?
Linguists tell us that Yahweh was one of many names for a primary pagan "god" known to all the ancient Semitic peoples before the birth of monotheism. The tribe of Levi, to which Moses belonged, knew the word and was aware that it often was voiced in a shortened form as a sacred invocation -- Yo!, or Yah!, or Yahu! -- like a mantra. Curiously, the name of Moses' mother was Jochebed -- or Yokheved -- a word that is derived from Yahweh. Was there an echo of a more ancient matriarchal era in God's spoken name to Moses?"