Dictionary definition · castle
noun
- a large and stately mansion
- a large building formerly occupied by a ruler and fortified against attack
- (chess) the piece that can move any number of unoccupied squares in a direction parallel to the sides of the chessboard
- interchanging the positions of the king and a rook
verb
- move the king two squares toward a rook and in the same move the rook to the square next past the king
Source: Open English WordNet (CC BY 4.0).