'Royal house' in the Bible

Also the queen Vashti made a feast for the women of the royal house which belonged to king Ahasuerus.

So Esther was taken to king Ahasuerus, into his royal house, in the tenth month, that is, the month Tebeth, in the seventh year of his reign.

And it came to pass on the third day, that Esther put on royal apparel, and stood in the inner court of the king's house, over against the king's house. And the king sat upon his royal throne in the royal house, over against the entrance to the house.