ADONAI ə dō’ nī, əd ō nā’ ī (אֲדֹנָי, H151). A divine name, tr. “the Lord,” and signifying “sovereignty,” “master.” Its etymology is obscure, but its meaning is certain—God is the ruling Lord. It appears first in
L. Koehler,Theology (1957), 30; J. B. Payne, The Theology of the Older Testament (1962), 146, 147.
International Standard Bible Encyclopedia (1915)
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 Names of God.