n. 1.a large and stately mansion 2.a large building formerly occupied by a ruler and fortified against attack 3.(chess) the piece that can move any number of unoccupied squares in a direction parallel to the sides of the chessboard 4.interchanging the positions of the king and a rook castle v. 1.move the king two squares toward a rook and in the same move the rook to the square next past the king
