The definition of a castle is a large fortified building or set of buildings where royalty lives, or a large and impressive house.(noun)
To castle is a move in chess involving the rook chess piece.(verb)
An example of castle is to move the king piece two squares and place the nearest rook on the square which was jumped by the king.
See castle in Webster's New World College Dictionary
Origin: ME < OE & Anglo-Fr castel < L castellum, dim. of castrum, fort
See castle in American Heritage Dictionary 4
Origin: Middle English castel
Origin: , from Old English
Origin: and from Norman French
Origin: , both from Latin castellum
Origin: , diminutive of castrum; see kes- in Indo-European roots.
Learn more about castle