- 1a large strong building with thick high walls and towers, built in the past by kings or queens, or other important people, to defend themselves against attack Windsor Castle a medieval castle see sandcastle
- 2(also rook) (in chess) any of the four pieces placed in the corner squares of the board at the start of the game, usually made to look like a castle Idioms
(to have) plans or dreams that are not likely to happen or come true As a child he would wander around the docks, building castles in the air about owning a boat one day.
a person's home is a place where they can be private and safe and do as they like
Check pronunciation: castle