Adonai is a term of Hebrew origin meaning “my Lord”. This was the name of God used in the Old Testament instead of the divine name of Yahweh (Yahweh), since the latter, out of respect, should not be pronounced.

Adonai reflects the superiority of God, replacing the Tetragrammaton YHWH, or Yahweh. Thus, whenever the tetragrammaton appeared in a biblical text, it was read as “Adonai”. Often the tetragrammaton is replaced by the Hebrew word HaShem, which means “The Name”.
According to Jewish tradition, the word Adonai, since it refers to God, should also not be used lightly, nor should it be used in inappropriate places, such as toilets.

The word Adonai is often used in expressions referring to characteristics of God. For example: Shalom Adonai is an expression that means “the peace of the Lord”. It is a greeting that mentions peace, as if to say “the peace of God be with you”. The response to this greeting should be “Adonai Shalom”.
The expression “Adonai Kadesh” is related to the Holiness of God, and means “The Lord is Holy”.