This word occurs in the Masoretic text 315 times by the side of the Tetragram YHWH (310 times preceding and five times succeeding it) and 134 times without it. Originally an appellation of God, the word became a definite title, and when the Tetragram became too holy for utterance Adonai was substituted for it, so that, as a rule, the name written YHWH receives the points of Adonai and is read Adonai, except in cases where Adonai precedes or succeeds it in the text, when it is read Elohim.
The vowel-signs e, o, a, given to the Tetragrammaton in the written text, therefore, indicate this pronunciation, Aedonai, while the form Jehovah, introduced by a Christian writer about 1520, rests on a misunderstanding. The translation of YHWH by the word Lord in the King James's and in other versions is due to the traditional reading of the Tetragrammaton as Adonai, and this can be traced to the oldest translation of the Bible, the Septuagint.
About the pronunciation of the Shem ha-Meforash, the "distinctive name" YHWH, there is no authentic information. In the early period of the Second Temple the Name was still in common use, as may be learned from such proper names as Jehohanan, or from liturgical formulas, such as Halelu-Yah. At the beginning of the Hellenistic era, however, the use of the Name was reserved for the Temple. From Sifre to Num. vi. 27, Mishnah Tamid, vii. 2, and Soṭah, vii. 6 it appears that the priests were allowed to pronounce the Name at the benediction only in the Temple; elsewhere they were obliged to use the appellative name (kinnuy) "Adonai."