Definition of castle
(Entry 1 of 2)
1a
: a large fortified building or set of buildings
b
: a massive or imposing house
2
: a retreat safe against intrusion or invasion
3
: rook entry 3
castle
verbDefinition of castle (Entry 2 of 2)
: to move a chess king two squares toward a rook and in the same move the rook to the square next past the king
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Merriam-Webster unabridged
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Time Traveler for castle
The first known use of castle was before the 12th century
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