castor

/ˈkɑːs.tə/

//ˈkɑːs.tə// noun

By · According to Wiktionary data (CC BY-SA) ·

"castor" is a 6-letter English headword indexed on PlainSpell.

The verdict

“castor” has 8 generated spelling variants in the English index at frequency #22,921. The variants make it a useful spelling check.

#22,921
frequency rank, English
5,599
“C” headwords
8
tracked misspellings
19
confusable pairs

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - A hat made from the fur of the beaver.

Corpus desk

Index EN-castor · castor · English

castor · rank #22,921 · 8 variants · 19 confusables

  • FREQ-MID #22,921
  • LEN-LONG 6 letters
  • VOW-2 2 vowels
  • CONFUS-HIGH 19 pairs
  • VAR-MID 8 variants
  • BOOK-DENSE 5,599
  • PHOTO-FINISH carp

Nearest frequency peer: carp (-1 rank slots)

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Rank peers near misspelling magnet “castor”

Same rarity band: useful when a typo lands on a peer headword

corpus weight

What this shows “castor” sits among these FrequencyWords peers; misspelling depth is tracked separately in the edit-distance chart.

Source FrequencyWords open word-frequency list As of September 3, 2026

Visual similarity to commonly confused words

How many letter changes separate each confused pair (Levenshtein distance, normalized).

castor vs Cato
50% similar
castor vs cater
67% similar
castor vs custom
67% similar

Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).

Key facts for castor
PropertyValue
Headwordcastor
LanguageEnglish
Part of speechNoun
IPA/ˈkɑːs.tə/
Letters6
Frequency rank#22,921
Misspellings tracked8
Confusable pairs19
SourceWiktionary (kaikki.org)

Frequency seat of misspelling magnet “castor”

Word frequency stretches from the small set of words we reach for constantly (left) out to the long tail barely used once in a while (right).castorlands here:

#1#100#1K#10K#100K
← used constantlyrarely used →

The axis is logarithmic, with each marked tick roughly ten times rarer than the last. Same rarity band neighbours include “carp” (#22,920), “Cahill” (#22,919), “BYU” (#22,918). Among 5,599 “C” headwords, “castor” is #22,921. Source: FrequencyWords open word-frequency list.

A misspelling magnet

The generator records 8 spelling variants around castor (IPA /ˈkɑːs.tə/), anoun. Corpus frequency is #22,921 among 5,599 “C” headwords. Wiktionary lists 4 senses, so context still picks the gloss.

Our generated misspelling index lists 8 likely wrong-spelling variants for castor, with forms such as "acstor", "casotr", and "casstor". Each variant is a distinct typo pattern an edit-distance generator flags, typically a doubled-consonant error, a silent-letter drop, or a vowel substitution. It also participates in 19 confusable-pair relationships, "Cato", "cater", "custom", and more, a pairing that trips writers up because the two words share enough sound or shape to blur together.

Etymologically, the entry records: From Middle French castor, from Old French castor (“beaver”), from Latin castor (“beaver”), from Ancient Greek κάστωρ (kástōr), from Doric Greek κάστον (káston, “wood”). The correct English form is castor, spelled C-A-S-T-O-R.

Definition

  1. 1
    A hat made from the fur of the beaver.
  2. 2
    A heavy quality of broadcloth for overcoats.
  3. 3
    Castoreum (bitter exudate of mature beavers).
  4. 4
    Any of various nymphalid butterflies of the genus Ariadne, of Africa and Asia.

Recorded use

Wiktionary example

These source excerpts show how castor appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. I have been always noted for the jaunty manner in which I wear my castor—[…]

Etymology

From Middle French castor, from Old French castor (“beaver”), from Latin castor (“beaver”), from Ancient Greek κάστωρ (kástōr), from Doric Greek κάστον (káston, “wood”).

Synonyms

beavercastoreumbeaver

Common misspellings

Also misspelled as:

  • acstor
  • casotr
  • casstor
  • castorr
  • casttor
  • catsor
  • ccastor
  • csator

Misspelling Pattern Breakdown

How far each generated variant is from the correct spelling of castor - counted as single-character edits (an insertion, a deletion, or a substituted letter). The larger the bar, the easier the typo is to spot; one-edit slips are the ones that sneak past readers.

acstor2casotr2casstor1castorr1casttor1catsor2ccastor1csator2
Edit distance from "castor"

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "castor"?
"castor" is spelled C-A-S-T-O-R. The IPA pronunciation is /ˈkɑːs.tə/.
What does "castor" mean?
As a noun, "castor" means: A hat made from the fur of the beaver.
What words are commonly confused with "castor"?
"castor" is commonly confused with "Cato", "cater", "custom". These words look or sound similar but have different meanings. PlainSpell provides detailed comparisons for each pair.
How do you pronounce "castor"?
The IPA (International Phonetic Alphabet) transcription for "castor" is /ˈkɑːs.tə/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "castor"?
From Middle French castor, from Old French castor (“beaver”), from Latin castor (“beaver”), from Ancient Greek κάστωρ (kástōr), from Doric Greek κάστον (káston, “wood”). See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "castor", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 6 letters (nearest by frequency rank).

Cahill#22,919Cicero#22,925bruise#22,909concur#22,936

Similar misspelling depth

Headwords with a similar count of attested misspellings (8 here; floor ≥5).

bumpy8 variantsbullion8 variantsBasque8 variantsdilute8 variants

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list