castle

castle — noun

1. a strong stone building with thick walls, built centuries ago by a ruler to prov

1.nounA2
Definition

a strong stone building with thick walls, built centuries ago by a ruler to provide safety for the people inside during war

Example

The king ordered his men to build a new castle on the hill above the river.

castle on the hill; passive: castle was built

Tourists walked through the old castle and admired the tall stone towers.

Common collocations
  • build a castle
  • defend a castle
  • besiege a castle
  • stone castle
  • medieval castle
  • castle wall
  • castle gate
Synonyms
  • fortress

    suggests a purely military stronghold, often less comfortable than a castle

  • palace

    a large grand home for a ruler, focused on living space rather than defence

  • stronghold

    emphasises the military-defensive purpose more than the building itself

Grammar Patterns

castle + of + [owner/place]

Usage Note

Countable only. Used literally for medieval fortifications; also used figuratively for any place that feels safe or grand.

Common Mistakes

We visited a old castle on the hill.
We visited an old castle on the hill.
'castle' starts with a consonant sound, so it takes 'a', but 'old' starts with a vowel sound, so before 'old castle' use 'an'.
The castle has many strong.
The castle has many strong walls.
'strong' is an adjective and needs a noun to modify.

2. the everyday, casual word for the rook — the chess piece that starts in the four

2.noun
Definition

the everyday, casual word for the rook — the chess piece that starts in the four corners of the board and moves straight along rows or columns, usually shaped like a small tower

Example

Diego moved his castle across the board to attack Leila's queen.

collocation: move your castle across the board

In the final match, Yara angled her castle along the seventh rank to trap Kofi's bishop.

castle controls a rank; collocation: trap [piece]

Common collocations
  • move a castle
  • capture with a castle
  • castle on the queenside
  • castle on the kingside
Synonyms
  • rook

    formal term; always used in official chess rules and tournament settings

Usage Note

This is the casual, spoken term for the rook. In tournaments and written notation, always use 'rook'. Beginners often prefer 'castle' because the piece looks like one.

Common Mistakes

The castle can move in a diagonal line.
The castle can move sideways or forwards in a straight line.
A rook moves in ranks and files (straight), not diagonally like a bishop.
Idioms

build castles in the air

idiom

to have plans, dreams, or hopes that are unlikely to become real

Ravi spent hours imagining he was a famous singer, but his father told him not to build castles in the air.

Instead of building castles in the air, Yasmin sat down and wrote a real plan for her small business.

a person's home is their castle

idiom

used to say that a person's home is a private, safe place where they can do as they please

Lin believes a person's home is their castle and refuses to let anyone enter without permission.

The old saying "An Englishman's home is his castle" reminds us that everyone deserves privacy in their own house.

(build) castles in the air

idiom

To have hopes or plans that are very unlikely to become real.

Mia spent her youth building castles in the air about becoming a famous singer.

Instead of studying, Diego builds castles in the air about winning the lottery.

a man’s home is his castle

idiom

A person's home is a private place where they can feel safe and do what they want.

After a long day at work, Brian relaxes at home because a man's home is his castle.

Sara believes a man's home is his castle, so she never enters without knocking.

castle — verb

Word family

  • castled
    adjectiveC1
  • castellated
    adjectiveC2

Synonym discussion

Sense: noun/1

A castle is a large fortified building built in the past for defence (e.g. 'The castle had a drawbridge and a moat.'). A fortress is a purely military structure designed to withstand attack — it often has thicker walls and fewer living comforts than a castle ('The army retreated to a mountain fortress.'). A palace is a grand residence for royalty or leaders; unlike a castle, a palace prioritises luxury and living space over defence ('The queen lived in a palace with beautiful gardens.'). A stronghold focuses on the defensive role: any place that is hard to attack ('The rebels held the hilltop stronghold for weeks.'). Use castle for medieval fortified homes, fortress for heavy military defences, palace for royal homes, and stronghold for any safe defensive position.

castle ↗fortresspalace ↗stronghold ↗

Common collocations

Nouns

  • castle gate
  • castle wall
  • castle tower
  • castle grounds
  • castle ruins

Phrases

  • king of the castle
  • castle in the air

Prepositions

  • in a castle
  • at a castle
  • inside a castle
  • outside a castle
  • near a castle

Etymology

LatinFrenchEnglish

From Latin 'castellum' (a fortified place, a little fort), a diminutive of 'castrum' (a camp, a military fort). The word passed through Old French 'castel' before entering Middle English as 'castel'. The chess meaning (noun sense 2 and verb sense 1) developed around the 1600s, when the game spread across Europe and the piece's tower-like shape reminded players of a castle.