from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A large fortified building or group of buildings with thick walls, usually dominating the surrounding country.
  • noun A fortified stronghold converted to residential use.
  • noun A large ornate building similar to or resembling a fortified stronghold.
  • noun A place of privacy, security, or refuge.
  • intransitive verb To move the king in chess from its own square two empty squares to one side and then, in the same move, bring the rook from that side to the square immediately past the new position of the king.
  • intransitive verb To place in or as if in a castle.
  • intransitive verb Games To move (the king in chess) by castling.

from The Century Dictionary.

  • In chess, to move the king from his own square two squares to the right or left, and bring the rook or castle to the square the king has passed over.
  • noun A building, or series of connected buildings, fortified for defense against an enemy; a fortified residence; a fortress.
  • noun In heraldry, a representation of two or more towers connected by curtains, often having a gateway in one of the curtains, and always embattled.
  • noun The house or mansion of a person of rank or wealth: somewhat vaguely applied, but usually to a large and more or less imposing building.
  • noun A piece made in the form of a castle, donjon, or tower, used in the game of chess; the rook.
  • noun A kind of helmet.
  • noun Nautical, a kind of fighting-tower formerly erected on war-galleys, etc., near the bow and stern, and called respectively forecastle and aftcastle. See cut under cadenas.
  • noun Synonyms See fortification.

from the GNU version of the Collaborative International Dictionary of English.

  • intransitive verb (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.
  • noun A fortified residence, especially that of a prince or nobleman; a fortress.
  • noun Any strong, imposing, and stately mansion.
  • noun A small tower, as on a ship, or an elephant's back.
  • noun A piece, made to represent a castle, used in the game of chess; a rook.
  • noun a visionary project; a baseless scheme; an air castle; -- sometimes called a castle in Spain (F. Château en Espagne).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A large building that is fortified and contains many defences; in previous ages often inhabited by a nobleman or king.
  • noun chess An instance of castling.
  • noun chess, informal A rook; a chess piece shaped like a castle tower.
  • noun obsolete A close helmet.
  • verb chess To perform the move of castling.
  • verb cricket To bowl a batsman with a full-length ball or yorker such that the stumps are knocked over.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a large building formerly occupied by a ruler and fortified against attack
  • noun a large and stately mansion
  • verb move the king two squares toward a rook and in the same move the rook to the square next past the king
  • noun interchanging the positions of the king and a rook
  • noun (chess) the piece that can move any number of unoccupied squares in a direction parallel to the sides of the chessboard


from The American Heritage® Dictionary of the English Language, 4th Edition

[Middle English castel, from Old English and from Norman French, both from Latin castellum, diminutive of castrum; see kes- in Indo-European roots.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Middle English castle, castel, from Old English castel, castell, cæstel, ċeastel ("a town, village, castle"), borrowed from Late Latin castellum ("small camp, fort"), diminutive of Latin castrum ("camp, fort, citadel, stronghold"), possibly from Proto-Indo-European *kat- (“hut, shed”). Parallel borrowings (from Late Latin or Old French) are Scots castel, castell ("castle"), West Frisian kastiel ("castle"), Dutch kasteel ("castle"), German Kastell ("castle"), Danish kastel ("citadel"), Swedish kastell ("citadel"), Icelandic kastali ("castle"). The Middle English word was reinforced by Anglo-Norman/Old Northern French castel, itself from Late Latin castellum ("small camp, fort") (compare modern French château from Old French chastel). If Latin castrum ("camp, fort, citadel, stronghold") is from Proto-Indo-European *kat- (“hut, shed”), Latin casa ("cottage, hut") is related. Possibly related also to Gothic  (hēþjō, "chamber"), Old English heaþor ("restraint, confinement, enclosure, prison"). See also casino, cassock.


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  • A properly fortified military residence, derived from Latin castellum.

    August 24, 2008

  • "Castles were good for keeping out the enemy, but there were few other benefits from living in a large damp pile of stones, and as times grew more peaceful from around the 16th century, the landed gentry started to build fine residences - known simply as 'country houses'."

    - multiple authors, 'Great Britain' (Lonely Planet guide).

    September 28, 2008