'Concubines' in the Bible

David took more concubines and wives from Jerusalem, after he came from Hebron; and more sons and daughters were born to him.

So the king left, and all his household with him. But the king left behind ten women who were concubines to take care of the house (palace).

Ahithophel said to Absalom, “Go in to your father’s concubines, whom he has left behind to take care of the house; then all Israel will hear that you have made yourself odious to your father. Then the hands of all who are with you will be strengthened [by your boldness and audacity].”

Then Joab came into the house to the king and said, “Today you have put all your servants to shame who this day have saved your life and the lives of your sons and your daughters, and the lives of your wives and concubines.

Then David came to his house (palace) at Jerusalem, and the king took the ten women, his concubines whom he had left to take care of the house, and placed them under guard and provided for them, but did not go in to them. So they were confined, and lived as widows until the day of their death.