castle

Etymology

From Middle English castle, castel, from late Old English castel, castell (“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”). Doublet of cashel, castell, castellum, and château. 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”), Welsh castell. 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 𐌷𐌴𐌸𐌾𐍉 (hēþjō, “chamber”), Old English heaþor (“restraint, confinement, enclosure, prison”). See also casino, cassock.

noun

1. A large residential building or compound that is fortified and contains many defences; in previous ages often inhabited by a nobleman or king. Also, a house or mansion with some of the architectural features of medieval castles.
2. (chess) An instance of castling.
3. (chess, informal) A rook; a chess piece shaped like a castle tower.
4. (shogi) A defense structure in shogi formed by defensive pieces surrounding the king.
5. (obsolete) A close helmet.
   The castle was perhaps a figurative name for a close headpiece deduced from its enclosing and defending the head, as a castle did the whole body; or a corruption from the Old French word casquetel, a small or light helmet. 1786, Francis Grose, A Treatise on Ancient Armour and Weapons, page 12
6. (dated) Any strong, imposing, and stately palace or mansion.
7. (dated) A small tower, as on a ship, or an elephant's back.
8. (cricket, colloquial) The wicket.
   Nay, he was quite an adept, and was very effective as a change bowler, for in no time he demolished the castle of any batsman. 1966, Gurdeep Singh, Cricket in Northern India, page 59

verb

1. (transitive) To house or keep in a castle.
   ...to encastle, to Castle. 1611, John Florio, Queen Anna's New World of Words, s.v. "Castellare"
   ...Some fierce tribe, castled on the mountain-peak... 1871, Robert Browning, Prince Hohenstiel-Schwangau, Saviour of Society, section 116
2. (transitive, figurative) To protect or separate in a similar way.
   Castle me in the armes of thy everlasting strength. 1655, William Gurnall, The Christian in Compleat Armour, 1st Pt., 32
3. (obsolete) To make into a castle: to build in the form of a castle or add (real or imitation) battlements to an existing building.
   ...Bake metes and dish metes... peynted and castelled with papir... c. 1386, Geoffrey Chaucer, “The Parson's Tale”, in Canterbury Tales
4. (usually intransitive, chess) To move the king 2 squares right or left and, in the same turn, the nearest rook to the far side of the king. The move now has special rules: the king cannot be in, go through, or end in check; the squares between the king and rook must be vacant; and neither piece may have been moved before castling.
   He [i.e., the king] may change (or Castle) with this Rooke, that is, he may goe two draughts at once towards this Rooke... causing the Rooke to stand next to him on either side. 1656, Gioachino Greco, translated by Francis Beale, The Royall Game of Chesse-Play, Being the Study of Biochimo, page 8
   No. 24. ¶ If your adversary make a false move, castle improperly, &c., you must take notice of such irregularity before you move, or even touch a piece, or you are no longer allowed to inflict any penalties. 1835, William Lewis, Chess for Beginners, Ch. 5, p. 24
5. (usually intransitive, shogi) To create a similar defensive position in Japanese chess through several moves.
6. (cricket) To bowl a batsman with a full-length ball or yorker such that the stumps are knocked over.
   And the 23-year-old brought the crowd to their feet when he castled Gayle's stumps, signalling the direction of the pavilion to his friend for good measure. 2009, “Lightning Bolt Blows Over Gayle”, in BBC Sport
   He bowled Vinay with a full, straight ball that castled off stump and then dished up a yorker that RP Singh backed away to and sent onto his stumps. 2011, Firdose Moonda, “A Day for Missed Hat-tricks”, in ESPNcricinfo