What does caster mean?
A caster is a small wheel, usually mounted in a pivoting fork or frame, that is fixed to the bottom of furniture, trolleys, hospital beds, and industrial equipment so that they can be moved with minimal effort. Because the frame swivels, the wheel can rotate freely in any direction, which is what allows an office chair or shopping trolley to change course smoothly. The word entered English in the eighteenth century, derived from the verb 'to cast,' reflecting the idea of something that turns or throws its load in a chosen direction. In British English, 'caster' (often spelled 'castor') has a second meaning: a small perforated shaker used at the table for sprinkling sugar, salt, or spices, giving rise to the term 'caster sugar' for finely ground sugar. Practical, unglamorous, and ubiquitous, the caster is a quiet workhorse of everyday movement — easy to overlook, but essential wherever heavy things need to roll rather than be lifted.
A small wheel mounted in a swivel frame and fixed to the base or legs of furniture or equipment to enable rolling movement.
"The delivery team screwed a new caster onto the broken leg of the filing cabinet."
Often used in the plural when describing a full set on one item of furniture.
(British English) A small container with a perforated top, used for sprinkling sugar, salt, pepper, or other seasonings at the table.
"Could you pass me the castor so I can sweeten my tea?"
Frequently spelled 'castor' in British English for this sense.
Standard plural; commonly used when referring to a complete set of wheels on a single piece of furniture or equipment.
"All four casters on the hospital bed were replaced during routine maintenance."
The humble caster under your office chair has been quietly doing its job since the 1870s — without it, moving a heavy desk would mean lifting instead of rolling.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of caster
Caster derives from the verb 'cast,' meaning to throw or turn, which itself traces back through Middle English and Old Norse 'kasta.' The noun form emerged in the early eighteenth century, first referring to a vessel from which liquid or seasoning was 'cast' out — hence the table sprinkler. By the nineteenth century the word had been applied to the revolving wheel fittings on furniture, presumably because the wheel 'casts' or turns in any direction. It shares its Germanic root with related words such as forecast, broadcast, and overcast, all built on the same verb.
How caster is actually used
In American usage, 'caster' covers all senses. In British usage, 'castor' is often preferred for the table container ('castor sugar', 'castors' on a cruet set), while 'caster' remains common for the wheel sense on both sides of the Atlantic. The word is everyday and neutral in register.
Easily confused with caster
In American English 'caster' is the standard spelling for both the wheel and the sprinkling bottle, while British English typically uses 'castor' (as in 'castor sugar'), though 'caster' is also accepted.
The castor bean is a plant seed from which castor oil is made; this spelling refers to the plant, not to wheels or tableware.