castle

(transitive) To house or keep in a castle.

(transitive, figuratively) To protect or separate in a similar way.

(obsolete) To make into a castle: to build in the form of a castle or add (real or imitation) battlements to an existing building.

(usually intransitive, chess) To move the king 2 squares right or left and, in the same turn, the nearest rook to the far side of the king. The move now has special rules: the king cannot be in, go through, or end in check; the squares between the king and rook must be vacant; and neither piece may have been moved before castling.

(usually intransitive, shogi) To create a similar defensive position in Japanese chess through several moves.

(cricket) To bowl a batsman with a full-length ball or yorker such that the stumps are knocked over.