castor

IPA/ˈkɑːstə(r)/
KK[kˈæstɚ]IPA/ˈkæstər/

castor — noun

  • castorsingular
  • castorsplural

1. a small turning wheel attached under the legs or base of a table, chair, or simi

1.nounB2
Definition

a small turning wheel attached under the legs or base of a table, chair, or similar item, so that you can slide the object from one place to another easily.

Example

The new office chairs have five black castors that glide smoothly over the carpet.

collocation: castors + glide smoothly

Aiko fitted lockable castors to her bookshelf so she could move it into the corner.

passive: fitted to [object]

Common collocations
  • swivel castors
  • lockable castors
  • castors on a chair
  • set of castors
  • furniture castors
  • castor glide
Synonyms
  • caster

    Variant spelling, standard in American English; refers to the same object.

  • wheel

    Much broader term — a wheel can be on a car or bicycle; a castor is specifically a small furniture wheel that usually swivels.

  • roller

    More general — can refer to paint rollers, conveyor rollers, or cylindrical objects that roll; less precise for furniture parts.

Grammar Patterns

a set of castors

castors on [furniture]

Usage Note

Usually used in the plural (castors) because furniture typically has a set of two or more. The spelling caster is common in American English and is equally correct.

Common Mistakes

I need a castor for my new desk.
I need a set of castors for my new desk.
Castors almost always come in a set; using the singular can sound odd when referring to the furniture item as a whole.
The drawer slides on castor wheels.
The drawer slides on castors.
Castor wheel is redundant; castor already means a wheel for furniture.

Word family

Synonym discussion

Sense: noun/1

A castor (or caster in US English) is a specific kind of small wheel designed to be attached to the legs or base of furniture so it can be moved without lifting. Unlike a regular wheel, which usually turns on a fixed axle, a castor is mounted in a bracket that swivels, letting you push the furniture in any direction. Roller is a much broader term that covers any cylindrical object that rolls — from paint rollers to conveyor-belt rollers — so it lacks the precision of castor when talking about furniture parts. For example, you would say 'the office chair has five castors' not 'five rollers', and you would talk about 'the wheels on a car' not 'the castors on a car'.

caster ↗wheel ↗roller ↗

Common collocations

Nouns

Phrases

  • a set of castors
  • castors that swivel

Prepositions

Etymology

Old NorseEnglish

The furniture sense of castor (often spelled caster) is thought to come from the verb cast, meaning 'to throw or turn' — referring to the wheel's ability to turn freely in any direction. This is a separate word from castor meaning 'beaver' (from Latin castor, Greek kastōr) and from castor as in castor oil (from the castor-oil plant). The spelling caster first appeared in the 17th century for a small wheel on furniture, and the variant castor followed soon after.