1 a large building with high walls and towers that was built in the past to defend people against attack 堡垒；城堡: a medieval castle 中世纪城堡Edinburgh Castle 爱丁堡古堡

2 in the game of 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 （国际象棋的）车