n. - A fortified residence, especially that of a prince or nobleman; a fortress.
n. - Any strong, imposing, and stately mansion.
n. - A small tower, as on a ship, or an elephant's back.
n. - A piece, made to represent a castle, used in the game of chess; a rook.
v. i. - To move the castle to the square next to king, and then the king around the castle to the square next beyond it, for the purpose of covering the king.