'Mistress' in the Bible

And he went in unto Hagar, and she conceived: and when she saw that she had conceived, her mistress was despised in her eyes.

And he said, Hagar, Sarai's maid, whence camest thou? and whither wilt thou go? And she said, I flee from the face of my mistress Sarai.

And the angel of the LORD said unto her, Return to thy mistress, and submit thyself under her hands.