Adonai

a-do'-ni, ad-o-na'-i ('adhonay):

A Divine name, translated "Lord," and signifying, from its derivation, "sovereignty." Its vowels are found in the Massoretic Text with the unpronounceable tetragrammaton " YHWH "; and when the Hebrew reader came to these letters, he always substituted in pronunciation the word " 'adhonay." Its vowels combined with the tetragrammaton form the word "Yahweh (Yahweh)."

See GOD, NAMES OF.