What is Castled?

Castled definition and meaning on Dictionary terms:

a fortified, usually walled residence, as of a prince or noble in feudal times.
the chief and strongest part of the fortifications of a medieval city.
a strongly fortified, permanently garrisoned stronghold.
a large and stately residence, especially one, with high walls and towers, that imitates the form of a medieval castle.
any place providing security and privacy: It may be small, but my home is my castle.
Chess. the rook.