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• castle
  castle

  noun

  a fortified, usually walled residence, as of a prince or noble in feudal times.
• Castle
  Castle

  noun

  Irene (Foote), 1893–1969, born in the U.S., and her husband and partner Vernon (Vernon Castle Blythe ), 1887–1918, born in England, U.S. ballroom dancers.

castle

¹ American  

[kas-uhl, kah-suhl] / ˈkæs əl, ˈkɑ səl /

noun

1. a fortified, usually walled residence, as of a prince or noble in feudal times.

   Synonyms:

   citadel, fortress

2. the chief and strongest part of the fortifications of a medieval city.

3. a strongly fortified, permanently garrisoned stronghold.

4. a large and stately residence, especially one, with high walls and towers, that imitates the form of a medieval castle.

   Synonyms:

   château, palace

5. any place providing security and privacy.

   It may be small, but my home is my castle.

6. Chess. the rook.

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verb (used with object)

castled, castling

1. to place or enclose in or as in a castle.

2. Chess. to move (the king) in castling.

verb (used without object)

Chess.

castled, castling

1. to move the king two squares horizontally and bring the appropriate rook to the square the king has passed over.

2. (of the king) to be moved in this manner.

Castle ² American  

[kas-uhl, kah-suhl] / ˈkæs əl, ˈkɑ səl /

noun

1. Irene (Foote), 1893–1969, born in the U.S., and her husband and partner Vernon (Vernon Castle Blythe ), 1887–1918, born in England, U.S. ballroom dancers.

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castle British  

/ ˈkɑːsəl /

noun

1. a fortified building or set of buildings, usually permanently garrisoned, as in medieval Europe

2. any fortified place or structure

3. a large magnificent house, esp when the present or former home of a nobleman or prince

4. the citadel and strongest part of the fortifications of a medieval town

5. chess another name for rook 2

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verb

1. chess to move (the king) two squares laterally on the first rank and place the nearest rook on the square passed over by the king, either towards the king's side ( castling short ) or the queen's side ( castling long )

Other Word Forms

Derived Forms

• castlelike
  adjective
• uncastled
  adjective

Etymology

Origin of castle

before 1000; Middle English, Old English castel < Latin castellum castellum

Explanation

A castle is a huge, grand home where a king or queen might live. Almost all castles are also fortified against attacks by enemy armies. Most castles were built in the Middle Ages by royalty or other nobility. You can still visit many historic castles in Europe, most of them built of stone and including details like towers and guardhouses. You can also call the chess piece known as a "rook" a castle, for its castle-like shape. The word has an Old English root, castel, or "village."

Example Sentences

Israeli troops on Sunday seized the Beaufort castle, which commands sweeping views of south Lebanon.

From Barron's • Jun. 2, 2026

Crawford suggested that the area could have been turned into a tourist visitors' centre, mainly for the days the castle is not open.

From BBC • Jun. 1, 2026

Israeli troops captured the castle from Palestinian militants during the 1982 Lebanon war and held the site until 2000.

From The Wall Street Journal • May 31, 2026

“Hmmm yes moving to LA in a month and can only live in a fairy castle sos,” commented another.

From Los Angeles Times • May 21, 2026

“Point it toward that castle over there,” Jack said, and she pulled on the handle until they were pointed at the large stone fortress.

From "Half Upon a Time" by James Riley