From WordNet (r) 3.0 (2006) [wn]:
castle
n 1: a large and stately mansion [syn: palace, castle]
2: a large building formerly occupied by a ruler and fortified
against attack
3: (chess) the piece that can move any number of unoccupied
squares in a direction parallel to the sides of the
chessboard [syn: castle, rook]
4: interchanging the positions of the king and a rook [syn:
castle, castling]
v 1: move the king two squares toward a rook and in the same
move the rook to the square next past the king
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Castle \Cas"tle\, n. [AS. castel, fr. L. castellum, dim. of
castrum a fortified place, castle.]
1. A fortified residence, especially that of a prince or
nobleman; a fortress.
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The house of every one is to him castle and
fortress, as well for his defense againts injury and
violence, as for his repose. --Coke.
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Our castle's strength
Will laugh a siege to scorn. --Shak.
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Note: Originally the medi[ae]val castle was a single strong
tower or keep, with a palisaded inclosure around it and
inferior buidings, such as stables and the like, and
surrounded by a moat; then such a keep or donjon, with
courtyards or baileys and accessory buildings of
greater elaboration a great hall and a chapel, all
surrounded by defensive walls and a moat, with a
drawbridge, etc. Afterwards the name was retained by
large dwellings that had formerly been fortresses, or
by those which replaced ancient fortresses. A Donjon or
Keep, an irregular building containing the dwelling of
the lord and his family; B C Large round towers ferming
part of the donjon and of the exterior; D Square tower,
separating the two inner courts and forming part of the
donjon; E Chapel, whose apse forms a half-round tower,
F, on the exterior walls; G H Round towers on the
exterior walls; K Postern gate, reached from outside by
a removable fight of steps or inclined plane for
hoisting in stores, and leading to a court, L (see
small digagram) whose pavement is on a level with the
sill of the postern, but below the level of the larger
court, with which it communicates by a separately
fortified gateway; M Turret, containing spiral stairway
to all the stories of the great tower, B, and serving
also as a station for signal fire, banner, etc.; N
Turret with stairway for tower, C; O Echauguettes; P P
P Battlemants consisting of merlons and crenels
alternately, the merlons being pierced by loopholes; Q
Q Machicolations (those at Q defend the postern K); R
Outwork defending the approach, which is a road
ascending the hill and passing under all four faces of
the castle; S S Wall of the outer bailey. The road of
approach enters the bailey at T and passes thence into
the castle by the main entrance gateway (which is in
the wall between, and defended by the towers, C H) and
over two drawbridges and through fortified passages to
the inner court.
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2. Any strong, imposing, and stately mansion.
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3. A small tower, as on a ship, or an elephant's back.
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4. A piece, made to represent a castle, used in the game of
chess; a rook.
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Castle in the air, a visionary project; a baseless scheme;
an air castle; -- sometimes called a castle in Spain (F.
Ch[^a]teau en Espagne).
Syn: Fortress; fortification; citadel; stronghold. See
Fortress.
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From The Collaborative International Dictionary of English v.0.48 [gcide]:
Castle \Cas"tle\, v. i. [imp. & p. p. Castled; p. pr. & vb. n.
Castling.] (Chess)
To move the castle to the square next to king, and then the
king around the castle to the square next beyond it, for the
purpose of covering the king.
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