Definition of castle in US English:



  • 1A large building, typically of the medieval period, fortified against attack with thick walls, battlements, towers, and in many cases a moat.

    • ‘I sat in the guard barracks in the outer wall of the castle battlements.’
    • ‘Maura was sitting at his desk, reading from a book that was thicker than a wall of the castle.’
    • ‘Some time ago, in a country that does not really exist anymore, a man once stood upon the battlements of a castle and surveyed his handiwork.’
    • ‘Later, he began building model castles, surrounded by fortified emplacements, and he spent hours studying the virtually impregnable fortifications of Vauban.’
    • ‘Some very strongly fortified castles of this class have an additional wall set a short distance out from the main enceinte and concentric with it, the area between the two walls being termed the outer ward.’
    • ‘You will encounter large mountains, a factory complex, and the large ruins of a medieval castle.’
    • ‘One of the most familiar forms of fortification, the castle still symbolizes the entire medieval world and seems to define its military outlook.’
    • ‘In the heart of the state - the lands around Sofia and in Macedonia - fortified castles were erected to repel Byzantine attacks.’
    • ‘If they attacked the castle, she would most likely die in the battle.’
    • ‘Founded by William the Conqueror, the fine motte and bailey castle was popular with medieval monarchs, some of whom used it as a royal hunting lodge.’
    • ‘They were inside what was left of the walls of the castle, but the tower was some way distant.’
    • ‘The castle has six towers and some twenty distinct roof forms.’
    • ‘THE 5ft-thick walls of a medieval castle have seen the light of day again after centuries buried underground.’
    • ‘Equally important is establishing the supply lines of wood and stone essential for more sophisticated buildings and stronger castle fortifications.’
    • ‘At the heart of the inner ward was a large mound, which this year's dig has revealed covers the remains of a tower house - the castle's main building.’
    • ‘He had heard tales of labyrinthine passages built into the walls of noble castles, and knew that the Princess must know a secret control to open his room into such a passage.’
    • ‘In medieval tower houses and castles, the gentry and their servants often slept in the same room, separated only by curtains.’
    • ‘Here, you can see stone cannon balls built into the castle walls, defensive battlements and interior living quarters.’
    • ‘Medieval castles were also designed to be as inaccessible as possible, so look for angles that reveal the inhospitable surroundings and the drama of their location.’
    • ‘Defensive walls and ditches were found from the medieval castle, as well as arch and window mouldings and numerous rubbish pits full of food remains and pottery.’
    fortress, fort, stronghold, fortification, keep, citadel, fastness, tower, peel, palace, chateau, donjon
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    1. 1.1 A magnificent and imposing old mansion.
      in names ‘Castle Howard’
      • ‘Hopefully soon they would catch up to Ian's caravan, and would return to castle Laramont with Rana.’
      • ‘The real Grace Nugent been a near neighbor, living at Castle Nugent four miles north of Edgeworthstown.’
      • ‘Castle Howard is the property of the Howard family, while Harewood House and Burton Constable belong to trusts.’
      mansion, stately home, hall, manor, big house, manor house, country house, palace
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    2. 1.2Chess informal
      old-fashioned term for rook


[no object]often as noun castling
  • 1Make a special move (no more than once in a game by each player) in which the king is transferred from its original square two squares along the back rank toward a rook on its corner square which is then transferred to the square passed over by the king.

    • ‘And White lost more than a tempo, more like two or three since it took five bishop and knight moves to make the captures and Black did not lose a tempo with castling and only made two capturing moves with his rook and king.’
    • ‘First off, White can't use this imbalance before Black castles and begins to activate the Bishop, and White can't prevent Black from castling.’
    • ‘Also, he would like to clear the back rank before he castles to give his Rooks greater maneuverability.’
    • ‘There isn't anything happening on the kingside for either side. White hasn't castled, which means that his King is in the center.’
    • ‘At this point I think Black could simply castle when once again I see nothing wrong with his position.’
    1. 1.1with object Move (the king) by castling.
      • ‘This is a fight he CAN'T win since his King isn't castled and White has more pieces in play than Black does.’
      • ‘But if the kings are castled on opposite sides and the half-open file bears down on the enemy king, it's a big plus and can easily offset even doubled isolated pawns.’
      • ‘He is also ahead in development, and his King is safely castled.’
      • ‘If White's King was castled, then 4.Nxd6 would be equal.’
      • ‘‘He's just a crybaby if you ask me,’ the other spat as he castled his king.’


  • castles in the air (or in Spain)

    • Visionary unattainable schemes; daydreams.

      ‘my father built castles in the air about owning a boat’
      • ‘The neurotic is the type of person who's continuously building dream castles in the air.’
      • ‘Academics aren't the only people to build castles in the air, in fact the almost hypnotic nature of the internet makes it very conducive to castle-making.’
      • ‘if you have built castles in the air, your work need not be lost; that is where they should be. now put the foundations under them.’
      • ‘Please tell him just to gently post the mail into the box I have so willingly provided, and then tell him to be on his way, to beat his path away from my dreamy semi-consciousness, and leave me to my somnolence, my reverie of castles in the air.’
      • ‘Maybe the economy would be growing so fast the voters wouldn't even notice the collapse of all those tall castles in the air.’
      • ‘It will be nothing but building castles in the air.’
      • ‘In an interview with the on-line magazine of the newspaper, he said, ‘Instead of constructing castles in the air, we have to support harsh cuts.’’
      • ‘Others would listen spellbound, and describe Heidegger at length building elaborate conceptual castles in the air, only to tear them down a moment later.’
      • ‘With investment in public construction projects being so vague, Li stressed that many big construction investments at the time were castles in the air.’
      • ‘When you're building castles in the air there's little to recommend too much in the way of caution on their location, architecture or facilities.’
      ambition, aspiration, hope
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Late Old English: from Anglo-Norman French and Old Northern French castel, from Latin castellum, diminutive of castrum ‘fort’.