What is the meaning of Castle?

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.

An instance of castling.

A rook; a chess piece shaped like a castle tower.

A defense structure in shogi formed by defensive pieces surrounding the king.

A close helmet.

Any strong, imposing, and stately palace or mansion.

A small tower, as on a ship, or an elephant's back.

The wicket.

To house or keep in a castle.

To protect or separate in a similar way.

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

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.

To create a similar defensive position in Japanese chess through several moves.

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

Alternative form of castel

Source: wiktionary.org