'Mistress' in the Bible

He went in to Hagar, and she conceived; and when she saw that she had conceived, her mistress was despised in her sight.

He said, “Hagar, Sarai’s maid, where have you come from and where are you going?” And she said, “I am fleeing from the presence of my mistress Sarai.”

Then the angel of the Lord said to her, “Return to your mistress, and submit yourself to her authority.”