1. (

• palace ,
• castle ,

) a large and stately mansion ;

2. (

• castle

) a large building formerly occupied by a ruler and fortified against attack ;

3. (

• castle ,
• rook

) (chess) the piece that can move any number of unoccupied squares in a direction parallel to the sides of the chessboard ;

4. (

• castle ,
• castling

) interchanging the positions of the king and a rook ;

1. (

• castle

) move the king two squares toward a rook and in the same move the rook to the square next past the king ;