'Women concubines' in the Bible

And the king goeth out, and all his household at his feet, and the king leaveth 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.