castle (
http://definr.com/castle)
n 1: a large and stately mansion [syn:
palace]
2: a large building formerly occupied by a ruler and fortified
against attack
3: the chessman that can move any number of unoccupied squares
in a direction parallel to the sides of the chessboard
[syn:
rook]
4: interchanging the positions of the king and a rook [syn:
castling]
v : move the king two squares toward a rook and in the same
move the rook to the square next past the king; in chess