1. Interchanging the positions of the king and a rook
   "Her timely castling protected the king from the opponent's attack";
   - castle

1. (chess) move the king two squares toward a rook and in the same move the rook to the square next past the king
   "He castled early in the game to protect his king"

Derived forms: castlings

Type of: chess move, go, move

Encyclopedia: Castling, William