noun A large residential building or compound that is fortified and contains many defences; in previous ages often inhabited by a nobleman or king. Also, a house or mansion with some of the architectural features of medieval castles.
noun An instance of castling.
noun A rook; a chess piece shaped like a castle tower.
noun A defense structure in shogi formed by defensive pieces surrounding the king.
noun A close helmet.
noun Any strong, imposing, and stately palace or mansion.
noun A small tower, as on a ship, or an elephant's back.