'Women concubines' in the Bible

And the king went forth, and all his household after him. And the king left ten women, concubines, to keep the house.

And David cometh in unto his house at Jerusalem, and the king taketh the ten women-concubines -- whom he had left to keep the house, and putteth them in a house of ward, and sustaineth them, and unto them he hath not gone in, and they are shut up unto the day of their death, in widowhood living.