castle

1 of 2

noun

cas·​tle ˈka-səl 

1

a

: a large fortified building or set of buildings

b

: a massive or imposing house

2

: a retreat safe against intrusion or invasion

3

: rook entry 3

Illustration of castle

• 1 fortified approach
• 2 moat
• 3 drawbridge
• 4 ward
• 5 angle tower
• 6 donjon or keep
• 7 chapel
• 8 gallery

castle

2 of 2

verb

castled; castling ˈka-s(ə-)liŋ 

transitive verb

1

: to establish in a castle

2

: to move (the chess king) in castling

intransitive verb

: to move a chess king two squares toward a rook and in the same move the rook to the square next past the king

Synonyms of castle

Noun

• fortress
• stronghold
• citadel
• fortification
• bastion
• fort

Examples of castle in a Sentence

Noun

Millionaires built their castles along the lake.

the implacable attackers placed the castle under a prolonged siege

Recent Examples on the Web

Noun

The rousing trailer finds Prince Adam bored to death hiding out at a generic corporate desk job on Earth when his precious sword is discovered, which sends him on a wild odyssey back to the land of Eternia and its talking tigers, spaceships, gothic castles, and magic swords. —Jeff Spry, Space.com, 23 Jan. 2026

Back at the castle, where the only thing haunting them is the ghosts of slain reality stars, everybody huddles to try to figure out whether to go for Ron or Colton. —Tom Smyth, Vulture, 23 Jan. 2026

Verb

The proactive Axar Patel hit an aggressive 27 before being castled by Nathan Ellis. —Tim Ellis, Forbes, 4 Mar. 2025

For example, pawns could not move two squares on their first turn, and there was no similar rule for castling. —Dylan Loeb McClain, New York Times, 27 May 2023

Word History

Etymology

Noun

Middle English castel, from Old English, from Old French & Latin; Old French dialect (Norman-Picard) castel, from Latin castellum fortress, diminutive of castrum fortified place; perhaps akin to Latin castrare to castrate

First Known Use

Noun

before the 12th century, in the meaning defined at sense 1a

Verb

1611, in the meaning defined at transitive sense 1

Phrases Containing castle

• bouncy castle
• castle doctrine
• castle in Spain
• castle in the air
• castle rule
• sand castle

Rhymes for castle

• facile
• gracile
• hassall
• hassle
• passel
• tassel
• vassal
• fluorouracil
• thiouracil
• forecastle
• uracil
• propylthiouracil

Kids Definition

castle

noun

cas·​tle

ˈkas-əl

1

a

: a large building or group of buildings usually having high walls with towers and a surrounding moat for protection

b

: a large or impressive house

2

: rook entry 3

Etymology

Noun

Middle English castel "castle," from early French castel (same meaning), from Latin castellum "castle, fortress" — related to château