Caster or castor?
caster is a noun meaning “Someone or something that casts”; castor is a noun meaning “A hat made from the fur of the beaver”. In written English (wordfreq, 2021 data) castor is about as common as caster.
What is the difference between caster and castor?
| caster | castor | |
|---|---|---|
| Part of speech | noun, verb | noun |
| Meaning | Someone or something that casts A wheeled assembly attached to a larger object at its base to facilitate rolling. A caster usually consists of a wheel (which may be plastic, a hard elastomer… To act as a caster (wheeled assembly) | A hat made from the fur of the beaver A heavy quality of broadcloth for overcoats A variety of petalite found in Elba |
| Example | a caster of spells | none recorded |
| Forms | casters | castors |
| Pronunciation | /ˈkɑːstə(ɹ)/ /ˈkæstə(ɹ)/ /ˈkæstɚ/ | /ˈkɑːs.tə/ /ˈkæs.tɚ/ |
| In writing | 1.3 times per million words | 1.5 times per million words |
Sources: caster and castor in the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Every current meaning of caster and castor
caster
- 1
Someone or something that casts
a caster of spells
- 2
To act as a caster (wheeled assembly)
- 3
A wheeled assembly attached to a larger object at its base to facilitate rolling. A caster usually consists of a wheel (which may be plastic, a hard elastomer, or metal), an axle, a mounting…
Many office chairs roll on a set of casters
- 4
A shaker with a perforated top for sprinkling condiments such as sugar, salt, pepper, etc
a set of casters
- 5
A stand to hold a set of shakers or cruets
- 6
The angle of the axis around which a car's front wheels rotate when the steering wheel is turned, with a vertical axis being defined as zero caster
castor
- 1
A hat made from the fur of the beaver
- 2
A variety of petalite found in Elba
- 3
UKA pivoting roller attached to the bottom of furniture to allow it to be moved
- 4
A heavy quality of broadcloth for overcoats
- 5
UKA container with a perforated cap for sprinkling its contents, especially salt, pepper, etc
- 6
Castoreum (bitter exudate of mature beavers)
- 7
Any of various nymphalid butterflies of the genus Ariadne, of Africa and Asia
Source: the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); obsolete, archaic, dialect and rare senses left out.
Which is more common, caster or castor?
caster appears 1.3 times per million words; castor 1.5 times per million words.
caster 1.3 times per million wordscastor 1.5 times per million words
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How many people search caster vs castor?
“caster vs castor” is searched about 170 times a month on Google and 10 on Bing in the United States. Google counts close variants of a query together (“castor vs caster”, “caster or castor”).
Sources: Google Ads keyword data through DataForSEO and Microsoft Advertising keyword data through DataForSEO, the average month from September 2025 to August 2026.