Meaning of “castle” - Learner’s Dictionary

castle

noun [ C ] us uk /ˈkɑːsl/
The castle attracts more than 300,000 visitors a year.The house is modelled on a 16th century castle.The mist swirled round the castle.The castle dates from the 11th century.There was a flag flying above the castle.

A2 a large, strong building with towers and high walls, that was built in the past to protect the people inside from being attacked

(Definition of “castle” from the Cambridge Learner’s Dictionary © Cambridge University Press)